Re: [meteorite-list] Micromounts and weights - Standards Vary
I agree that if something is sold as a micro-mount with no weight specified then it is assumed the piece is small and can technically even be even as small as 1 mg.. although when selling mounts that have specified weights or ranges in weights it only makes sense that the actual specimen be that weight or fall into the range specified because if it doesn't then the item is being misrepresented regardlless if the seller eye balls the pieces or doesn't have a proper scale to weigh it. If you sell something to me personally at a certain weight it better weigh that much that is my expectation. If i buy something that is a micro-mount with no weight specified i usually ask the seller for an approximate weight to give me an idea of what i am buying and that is when i would get a weight that has a range for example 10 - 20 mg which is a rough estimation and that would give me an idea of the size of the mount.. but when people sell something with a specific weight or say that the weight is at least a certain amount then they are responsible to provide what they are selling rather then come up with lame excuses. Daniel Furlan __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Milligram Scale
Hi Don , Hi lists at http://www.sartorius-mechatronics.com/Mechatronics/DataSheets/English/Cubis/DS-Cubis-e.pdf you can download a sheet with sata of german lab gauges. m42protosun -Original-Nachricht- Subject: [meteorite-list] Milligram Scale Date: Fri, 01 Jul 2011 05:07:20 +0200 From: Don Merchant dmerc...@rochester.rr.com To: Meteorite-list@meteoritecentral.com Cc: Don Merchant dmerc...@rochester.rr.com Hi List. Can anyone recommend a decent scale that will read in milligrams. No cheapies please but rather something that is + - 2 milligrams, good quality and consistently accurate and I don't have to sell a lung on eBay to afford one. Doesn't have to exceed 20gms. Somewhere in the $150-250 range? Any thoughts to those that I see selling specimens in the milligram range. Thank you Sincerely Don Merchant __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list Postfach fast voll? Jetzt kostenlos E-Mail Adresse @t-online.de sichern und endlich Platz für tausende Mails haben. http://www.t-online.de/email-kostenlos __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] Rocks from Space Picture of the Day - July 1, 2011
http://www.rocksfromspace.org/July_1_2011.html __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] Identification techniques of possible Lunar material
First off, I'm still trying to figure out how to post to this list, so this is a test post and I apologize if I haven't completely adhered to the guidelines. I also may as well make this post practical, so I have a question I'd really appreciate any help with. My name is Chris Handler and I'm from Adelaide in Australia. I've had several meteorites for well beyond a decade, but I've only really started to collect seriously for a year now. In that time though I've had the pleasure of dealing from quite a few people within this community and I can say that every moment has been an enjoyable experience. I've been reading this list for some time now, as a lurker, but I've decided to come out of the shadows. With all this talk about Apollo dust and material lately, I thought that this question might be appropriate for now. Along with meteorites, I've always been enthralled by sample return missions and I collect what few artifacts turn up that have a direct relationship to SRM's. A while ago I acquired a sealed pack of five secondary sample bottles from the Lunar Receiving Lab. One of these bottles has some sort of inclusion impregnated into its rim. The inclusion is around a millimeter across and there is a clear puncture mark in the rim from where it entered. The five bottles are inside two separate plastic bags. The outer bag is thin and brittle with a couple of small holes in it. It is sealed shut with a cleaned for service sticker stating that it was cleaned on the 6/11/71, along with the number 2552 and the letters WSTF W/U. The second and inner bag however is a thick sterile bag that has been heat sealed. The bag does not loose air pressure even when I put weight on it for 24 hours, so the inclusion found its way there before it was sealed. Given what the bottles where used for and what the inclusion could possibly be, I really want to know if there is any possible way to identify something of this size and if that could be done through the plastic? I'm quite hesitant to remove it from the bottle because of one; the provenance, and two; I'd hate to damage an historic item like this and have it turn out to be a fragment of metal from a tool, or some other contaminant. If there was some way to confirm it is at least some sort of natural mineral, I'd consider having id exhumed and imaged at the local micro imaging lab here, and maybe that would allow comparison to Apollo material. I know that some micros like Lafayette and Chassigny commonly come in sizes similar to this inclusion, so is there a method to authenticate them at that size? I've attached a couple of photos below of what I was describing. The first is of the packet of bottles. The inclusion is in the one on the left hand side. http://i719.photobucket.com/albums/ww195/cmhandler/CSC_0146-3.jpg The next one is a macro photo of the inclusion with contrast enhancement. http://i719.photobucket.com/albums/ww195/cmhandler/CSC_0143-4.jpg The last shows the perforated opening where the inclusion penetrated the rim. http://i719.photobucket.com/albums/ww195/cmhandler/CSC_0136_1.jpg Thank you for taking the time to read this, I'd appreciate any help on this matter at all. Regards, Chris Handler __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Micromounts and weights - Standards Vary
Hi Doug and List, I also have a cheap Chinese jeweler's scale - my third one in 3 years. They seem to last about a year before crapping out. I realize it's not the most accurate instrument in the scientific world, but I don't keep time using an atomic watch either. I do own some calibration weights (not the ones that came with the scale), and I use these to test the accuracy of my scale. Thus far, it remains accurate to a mg or two and the specimens I get from other dealers (some of whom presumably have better scales than me) weigh what they are supposed to. So either my little Cathay scale is accurate enough, or everyone else's scales match the inaccuracies of my own. The scale Mike Bandli linked to is awesome, but unfortunately it costs more than my car is worth. If I could afford that scale, then most of my other non-meteorite problems would be solved. ;) I have a few reasons for not selling micros by weight and scale questions are one of those reasons. The milligram scale I own is mostly for my personal use. But one thing I think everyone agrees on is - if you say a given specimen weighs Xmg, then it should weigh Xmg, especially if the specimen is something rare and the buyer is paying a premium price per/mg. FWIW, even though I don't offer most micros by weight, I will weigh any specimen if a buyer requests it. Most don't care if a NWA chondrite micro weighs Xmg or (X +/-20)mg, as long as they feel like they got their money's worth, the specimen looks like what they expected based on the photos, and it fills a hole in their collection. Best regards, MikeG -- - Galactic Stone Ironworks - Meteorites Amber (Michael Gilmer) Website - http://www.galactic-stone.com Facebook - http://tinyurl.com/42h79my News Feed - http://www.galactic-stone.com/rss/126516 Twitter - http://twitter.com/galacticstone EOM - http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564 - On 7/1/11, MexicoDoug mexicod...@aim.com wrote: I have a cheap Chinese scale for which I paid under $20. I never thought to question its accuracy since I've never been in a position where 5mg either way made a difference. But, let me propose a solution for the occasional user who doesn't have hundreds of dollars burning a hole in their pocket for something they may not use as frequently as some of the dealers (who may need a calibrated scale for trade) and isn't keen on loading up on gadgets for their Swiss beauty. And who is up for some muted MacGyverish fun. I just cut 23.5 cm X 30 cm of aluminum foil. Mine was from Walmart, likely the lightest normal weight standard. It weighs 3.1 grams. That 3100 milligrams. It works out to 4.4 mg per square cm. So you can make your own set of standards that will be plenty accurate for these purposes. Calculate the areas of your standard set and consider it a primary standard (do use a decent scale if your repeat what I did for a sheet of your own aluminum foil. But don't get too worried: if mine were 3.0 grams instead of 3.1 grams it would still be 4.3mg/cm2. Now the fun part which you've figured out by now. Use that cheap scale and put approximately what the scale says the specimen weighs in standards on the scale. I.e., if you have a supposed 12 mg specimen, just put 12/4.4= 2.73 square cm, so put whatever you have that's close to 3 cm2 or just use a razor to trace around your scale cube bottom if you are in a hurry to make 1 cm2 cutouts. If you put exactly 3 cm2 in this example on the scale and it says 15 mg, you know your scale is 2 mg too high so just subtract 2mg to normalized the weight to your standard. Don't worry about the decimals - there rounding anyway and a ten-thousandth of a gram is a useless measure to you, anyway. As a matter of fact a mg or two, or even more depending, is iffy depending on the temperature, humidity etc etc. etc. Lots of splainin' above but it is really a cinch. A whole lot easier for me than dealing with a sensitive analytical balance under most circumstances. Analytical balances are cool but they have to be treated with incredible respect to be kept in calibration. The element on the cheapo scales responds to weights in that range so if you do something like this you will do just as well for the vast majority of purposes and you can go to WalMart and buy your custom standards for a buck or so, if you can't raid the pantry for them. Have fun using the heavier oven gauge foil if you are in a higher weight range - like 50-100 mg. The only drawback is humidity on the foil so keep it dry! Don't forget, a specimen in the 10 mg range can easily pick up 20% extra weight in water, etc. So if you are worried about that accuracy, you ought to be sticking your specimens in the oven and weighing them hot. Any analytical chemists here will remember the
Re: [meteorite-list] Micromounts and weights - Standards Vary
I use a multi-thousand dollar scale, you are right about the cheap scales, have bought several for the field, they are worthless. Wanna sell the small stuff, make the investment to do it right. Michael Farmer Sent from my iPad On Jun 30, 2011, at 4:52 PM, Mike Bandli fuzzf...@comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg, you need a machine that has been recently leveled and calibrated in-situ. I have a recently leveled/calibrated mechanical scale whose tare changes by the hour due to changes in the weather. It even picks up the subtle vibration of the dishwasher downstairs. Bottom line - a $100 mg scale isn't going to get you the accuracy needed to accurately measure true mg. Since most people can't afford the hundreds to thousands it costs for an accurate mg scale, I don't expect most mg weights advertised to be truly accurate. They're close... Just my 2 mg worth (+/- 1mg)... -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] On Behalf Of Michael Gilmer Sent: Thursday, June 30, 2011 4:17 PM To: Meteorite List Subject: [meteorite-list] Micromounts and weights - Standards Vary Hi Listees and Micronauts, There has been some discussion recently about people buying micromounts from a vendor on eBay and not getting the weights they were promised. I thought I would throw out some thoughts on micros, since those are my bread and butter. First, the definition of micromount is relative. There is no set-in-stone size bracket for what defines a micromount. It seems to me that the general consensus is that micromounts are in the 1g range for the more common types and sub-gram in weight for the rare types. Very rare falls or planetaries are commonly sold by the milligram. Rockhounds tend to equate meteorite micromounts with mineral thumbnails. But generally speaking, most micromounts on the market today are in the sub-gram (1g) range. Ideally, a micromount should be visually appealing (such a well polished, thin part slice with good surface area to weight ratio) and big enough to identify the lithology of the type/fall, while at the same time being cheap enough to afford on a limited budget. The more preparation that goes into making a given micromount, the higher the price, generally speaking. At some point, it's not financially viable to put a lot of cutting and polishing work into piece of common find that is only worth a buck or two a gram. Smaller micros are difficult to work with during preparation, for obvious reasons, so many of the micromounts seen on the market are unpolished, rough, or broken. What motivates a person to collect micromounts varies from person to person, but the most commonly cited reason for buying micros is to temporarily fill a void in a type collection. It could be a petrologic type, a find from a given geographic area, a fall from a specific date, etc. Often a micromount is a temporary measure until a nicer specimen can be acquired, or until the needed finances to buy a larger piece can be saved up. For the very rare types and planetaries, a micromount might be the best hope for a collector on a restricted budget. There are a couple of schools of thought when it comes to dealing and selling micromounts - some dealers sell specimens by weight (by milligram, even for specks) or some dealers offer specimens by the piece (by eye/photo). For the most part, I am of the latter school that sells micros by the piece. That means I don't weigh each and every micromount, unless it is a very rare and valuable meteorite such as a planetary or historical fall. Each dealer has their own methods for handling micromounts and we those aren't really relevant to the discussion at hand. When weighing micromounts, one must use an accurate scale that is sensitive to 1 milligram - the good ones are used by diamond and gem dealers. There are many brands of these scales which range in quality and accuracy. When dealing with small specks that weigh a milligram or two, the readings can vary from unit to unit when weighing the same specimen. If a
[meteorite-list] Test
Disregard __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] test
test __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] Micromounts and weights - Standards Vary
Hello Listers for those of you that dont have $1600 to spend on a scale here is a scale that is about $250. http://www.scalesolutionsllc.com/m8/VB-302A--vmc-vb-302a-balance.html Now for the cheaper scales that are $20 from China, I find that they are pretty accurate to about 6 to 8 mg and on up. To get the 1 to 5 mg weight you need to do a trick with the scale. What you do is zero out the scale and then put something on the scale like a small piece of paper that weights about 40 mg or so and then add the small mircomount and you will see the weight go up in 1mg increments from the original weight . It works wonders but double or tripple check the weight when your dealing with 1mg to 5mg samples. Shawn Alan IMCA 1633 eBaystore http://shop.ebay.com/photophlow/m.html [meteorite-list] Micromounts and weights - Standards VaryMike Bandli fuzzfoot at comcast.net Thu Jun 30 20:11:14 EDT 2011 Previous message: [meteorite-list] Micromounts and weights - Standards Vary Next message: [meteorite-list] Micromounts and weights - Standards Vary Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Yes, and for those serious about weights, I would highly recommend a refurbished Mettler unit similar to this one: http://tinyurl.com/3dz8udc -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: Michael Farmer [mailto:mike at meteoriteguy.com] Sent: Thursday, June 30, 2011 4:55 PM To: Mike Bandli Cc: Michael Gilmer; Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary I use a multi-thousand dollar scale, you are right about the cheap scales, have bought several for the field, they are worthless. Wanna sell the small stuff, make the investment to do it right. Michael Farmer Sent from my iPad On Jun 30, 2011, at 4:52 PM, Mike Bandli fuzzfoot at comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg, you need a machine that has been recently leveled and calibrated in-situ. I have a recently leveled/calibrated mechanical scale whose tare changes by the hour due to changes in the weather. It even picks up the subtle vibration of the dishwasher downstairs. Bottom line - a $100 mg scale isn't going to get you the accuracy needed to accurately measure true mg. Since most people can't afford the hundreds to thousands it costs for an accurate mg scale, I don't expect most mg weights advertised to be truly accurate. They're close... Just my 2 mg worth (+/- 1mg)... -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: meteorite-list-bounces at meteoritecentral.com [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Michael Gilmer Sent: Thursday, June 30, 2011 4:17 PM To: Meteorite List Subject: [meteorite-list] Micromounts and weights - Standards Vary Hi Listees and Micronauts, There has been some discussion recently about people buying micromounts from a vendor on eBay and not getting the weights they were promised. I thought I would throw out some thoughts on micros, since those are my bread and butter. First, the definition of micromount is relative. There is no set-in-stone size bracket for what defines a micromount. It seems to me that the general consensus is that micromounts are in the 1g range for the more common types and sub-gram in weight for the rare types. Very rare falls or planetaries are commonly sold by the milligram. Rockhounds tend to equate meteorite micromounts with mineral thumbnails. But generally speaking, most micromounts on the market today are in the sub-gram (1g) range. Ideally, a micromount should be visually appealing (such a well polished, thin part slice with good surface area to weight ratio) and big enough to identify the lithology of the type/fall, while at the same time being cheap enough to afford on a limited budget. The more preparation that
Re: [meteorite-list] Micromounts and weights - Standards Vary
Yikes, Dealers selling milligram specimens after weighing them on $20 flip open scales? All purchases of micro-mounts are suspended until further notice... -- Richard Kowalski Full Moon Photography IMCA #1081 __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Micromounts and weights - Standards Vary
Hi Mike and all, I absolutely agree. I used to use a $500 digital and now Use a $135 digital and I consider them both about as accurate As the other ~ deduct one decimal point for absolute accuracy. (it is likely far closer than that, but one should not proclaim a specific weight, IE .007g (7mg) unless one has a serious balance beam in an air tight setup. A royal pain in the a** And extremely costly. However, for the most part, I always sell micromounts - the Ones less than 10mg, based on VISUAL COMPARISON. That is What I look for for my own collection... If I want something that Is so small, then the size is far more important to me than the mass. BTW, a micromount has traditionally been defined as any Specimen that fits into an old style 1 X 1 square display box. The new, vastly superior membrane boxes are considerably larger And can hold a decent sized macromount equally well as a micromount. Best regards, Michael On 6/30/11 4:52 PM, Met. Mike Bandli fuzzf...@comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg, you need a machine that has been recently leveled and calibrated in-situ. I have a recently leveled/calibrated mechanical scale whose tare changes by the hour due to changes in the weather. It even picks up the subtle vibration of the dishwasher downstairs. Bottom line - a $100 mg scale isn't going to get you the accuracy needed to accurately measure true mg. Since most people can't afford the hundreds to thousands it costs for an accurate mg scale, I don't expect most mg weights advertised to be truly accurate. They're close... Just my 2 mg worth (+/- 1mg)... -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] On Behalf Of Michael Gilmer Sent: Thursday, June 30, 2011 4:17 PM To: Meteorite List Subject: [meteorite-list] Micromounts and weights - Standards Vary Hi Listees and Micronauts, There has been some discussion recently about people buying micromounts from a vendor on eBay and not getting the weights they were promised. I thought I would throw out some thoughts on micros, since those are my bread and butter. First, the definition of micromount is relative. There is no set-in-stone size bracket for what defines a micromount. It seems to me that the general consensus is that micromounts are in the 1g range for the more common types and sub-gram in weight for the rare types. Very rare falls or planetaries are commonly sold by the milligram. Rockhounds tend to equate meteorite micromounts with mineral thumbnails. But generally speaking, most micromounts on the market today are in the sub-gram (1g) range. Ideally, a micromount should be visually appealing (such a well polished, thin part slice with good surface area to weight ratio) and big enough to identify the lithology of the type/fall, while at the same time being cheap enough to afford on a limited budget. The more preparation that goes into making a given micromount, the higher the price, generally speaking. At some point, it's not financially viable to put a lot of cutting and polishing work into piece of common find that is only worth a buck or two a gram. Smaller micros are difficult to work with during preparation, for obvious reasons, so many of the micromounts seen on the market are unpolished, rough, or broken. What motivates a person to collect micromounts varies from person to person, but the most commonly cited reason for buying micros is to temporarily fill a void in a type collection. It could be a petrologic type, a find from a given geographic area, a fall from a specific date, etc. Often a micromount is a temporary measure until a nicer specimen can be acquired, or until the needed finances to buy a larger piece can be saved up. For the very rare types and planetaries, a micromount might be the best hope for a collector on a restricted budget. There are a couple of schools of thought when it comes to dealing and selling micromounts - some dealers sell specimens by weight (by milligram, even for specks) or some dealers offer specimens by the piece (by
Re: [meteorite-list] Micromounts and weights - Standards Vary
Hi All, Actually I always thought that trying to measure something like 0.001g is very difficult. If you measuring such a small thing on the same kind of spring scale at the sea level and at 500m above the sea level, the scale will show you a different result. Simple example: http://www.edinformatics.com/math_science/mass_weight.htm Best, Sergey -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com]On Behalf Of Michael Blood Sent: Friday, July 01, 2011 11:03 PM To: Met. Mike Bandli; 'Michael Farmer' Cc: Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Mike, I checked this out and was confused. The first statement: METTLER TOLEDO AT261 0.01mg Counting Scale in HardCase Implies accuracy down to a tenth of one mg! That is .0001g HOWEVER, the first part of the description reads: Weighing Capacity:205g Repeatability:(0-50g)+/-0.015mg Linearity:(10g)+/-0.03mg Stabilization:(typical)8-12sec What the h*** does that mean? It sounds like a maximum Capacity of 205g, but repeatability:(0-50g)+/- 0.015 seams Like it is saying it can be off by 15mg! THEN: Linearity:(10)+/- 0.03mg Stabilization... sounds Like they are saying it could be off by 30mg. How do others read this? Michael On 6/30/11 5:11 PM, Met. Mike Bandli fuzzf...@comcast.net wrote: Yes, and for those serious about weights, I would highly recommend a refurbished Mettler unit similar to this one: http://tinyurl.com/3dz8udc -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: Michael Farmer [mailto:m...@meteoriteguy.com] Sent: Thursday, June 30, 2011 4:55 PM To: Mike Bandli Cc: Michael Gilmer; Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary I use a multi-thousand dollar scale, you are right about the cheap scales, have bought several for the field, they are worthless. Wanna sell the small stuff, make the investment to do it right. Michael Farmer Sent from my iPad On Jun 30, 2011, at 4:52 PM, Mike Bandli fuzzf...@comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg, you need a machine that has been recently leveled and calibrated in-situ. I have a recently leveled/calibrated mechanical scale whose tare changes by the hour due to changes in the weather. It even picks up the subtle vibration of the dishwasher downstairs. Bottom line - a $100 mg scale isn't going to get you the accuracy needed to accurately measure true mg. Since most people can't afford the hundreds to thousands it costs for an accurate mg scale, I don't expect most mg weights advertised to be truly accurate. They're close... Just my 2 mg worth (+/- 1mg)... -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] On Behalf Of Michael Gilmer Sent: Thursday, June 30, 2011 4:17 PM To: Meteorite List Subject: [meteorite-list] Micromounts and weights - Standards Vary Hi Listees and Micronauts, There has been some discussion recently about people buying micromounts from a vendor on eBay and not getting the weights they were promised. I thought I would throw out some thoughts on micros, since those are my bread and butter. First, the definition of micromount is relative. There is no set-in-stone size bracket for what defines a micromount. It seems to me that the general consensus is that micromounts are in the 1g range for the more common types and sub-gram in weight for the rare types. Very rare falls or planetaries are commonly sold by the milligram. Rockhounds tend to equate meteorite micromounts with mineral thumbnails. But generally speaking, most micromounts on the market today are in the sub-gram (1g) range. Ideally, a micromount should be visually appealing (such a well polished, thin part slice with good surface area to weight ratio) and big enough to identify the lithology
Re: [meteorite-list] Micromounts and weights - Standards Vary
Hi Michael, That is +/- 0.015 of a *milligram*, not a gram, and 0.03 of a *milligram*, not a gram. Cheers, Mike -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited. -Original Message- From: Michael Blood [mailto:mlbl...@cox.net] Sent: Friday, July 01, 2011 2:03 PM To: Met. Mike Bandli; 'Michael Farmer' Cc: Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Mike, I checked this out and was confused. The first statement: METTLER TOLEDO AT261 0.01mg Counting Scale in HardCase Implies accuracy down to a tenth of one mg! That is .0001g HOWEVER, the first part of the description reads: Weighing Capacity:205g Repeatability:(0-50g)+/-0.015mg Linearity:(10g)+/-0.03mg Stabilization:(typical)8-12sec What the h*** does that mean? It sounds like a maximum Capacity of 205g, but repeatability:(0-50g)+/- 0.015 seams Like it is saying it can be off by 15mg! THEN: Linearity:(10)+/- 0.03mg Stabilization... sounds Like they are saying it could be off by 30mg. How do others read this? Michael On 6/30/11 5:11 PM, Met. Mike Bandli fuzzf...@comcast.net wrote: Yes, and for those serious about weights, I would highly recommend a refurbished Mettler unit similar to this one: http://tinyurl.com/3dz8udc -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: Michael Farmer [mailto:m...@meteoriteguy.com] Sent: Thursday, June 30, 2011 4:55 PM To: Mike Bandli Cc: Michael Gilmer; Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary I use a multi-thousand dollar scale, you are right about the cheap scales, have bought several for the field, they are worthless. Wanna sell the small stuff, make the investment to do it right. Michael Farmer Sent from my iPad On Jun 30, 2011, at 4:52 PM, Mike Bandli fuzzf...@comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg, you need a machine that has been recently leveled and calibrated in-situ. I have a recently leveled/calibrated mechanical scale whose tare changes by the hour due to changes in the weather. It even picks up the subtle vibration of the dishwasher downstairs. Bottom line - a $100 mg scale isn't going to get you the accuracy needed to accurately measure true mg. Since most people can't afford the hundreds to thousands it costs for an accurate mg scale, I don't expect most mg weights advertised to be truly accurate. They're close... Just my 2 mg worth (+/- 1mg)... -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] On Behalf Of Michael Gilmer Sent: Thursday, June 30, 2011 4:17 PM To: Meteorite List Subject: [meteorite-list] Micromounts and weights - Standards Vary Hi Listees and Micronauts, There has been some discussion recently about people buying micromounts from a vendor on eBay and not getting the weights they were promised. I thought I would throw out some thoughts on micros, since those are my bread and butter. First, the definition of micromount is relative. There is no set-in-stone size bracket for what defines a micromount. It seems to me that the general consensus is that micromounts are in the 1g
Re: [meteorite-list] Micromounts and weights - Standards Vary
If you measuring such a small thing on the same kind of spring scale at the sea level and at 500m above the sea level, the scale will show you a different result. Simple example: Hi Sergey, I think you want to clarify that. If you try to measure something that weighs 0.001 grams ( 1 mg ) at sea level vs. 500 meters higher, it will weigh 251 ng (nanograms) less, but still 1.000 mg = 0.99975 mg. That is not detectable by any conventional scale and other external factors like differences in air density, air saturation, convection, not to mention people walking around nearby, etc. will swamp the difference, not to mention the porosity of the sample itself which is a problem for even the regular fare. But - I think you meant trying to weigh something with the precision of 1 mg for macro sized samples is very difficult. In the case of a ten gram sample the 251 nanograms becomes 2.5 milligrams of difference, and you are right! Kindest wishes Doug -Original Message- From: Sergey Vasiliev vs.petrov...@gmail.com To: Michael Blood mlbl...@cox.net; Met. Mike Bandli fuzzf...@comcast.net; 'Michael Farmer' m...@meteoriteguy.com Cc: Meteorite List meteorite-list@meteoritecentral.com Sent: Fri, Jul 1, 2011 5:24 pm Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Hi All, Actually I always thought that trying to measure something like 0.001g is very difficult. If you measuring such a small thing on the same kind of spring scale at the sea level and at 500m above the sea level, the scale will show you a different result. Simple example: http://www.edinformatics.com/math_science/mass_weight.htm Best, Sergey -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com]On Behalf Of Michael Blood Sent: Friday, July 01, 2011 11:03 PM To: Met. Mike Bandli; 'Michael Farmer' Cc: Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Mike, I checked this out and was confused. The first statement: METTLER TOLEDO AT261 0.01mg Counting Scale in HardCase Implies accuracy down to a tenth of one mg! That is .0001g HOWEVER, the first part of the description reads: Weighing Capacity:205g Repeatability:(0-50g)+/-0.015mg Linearity:(10g)+/-0.03mg Stabilization:(typical)8-12sec What the h*** does that mean? It sounds like a maximum Capacity of 205g, but repeatability:(0-50g)+/- 0.015 seams Like it is saying it can be off by 15mg! THEN: Linearity:(10)+/- 0.03mg Stabilization... sounds Like they are saying it could be off by 30mg. How do others read this? Michael On 6/30/11 5:11 PM, Met. Mike Bandli fuzzf...@comcast.net wrote: Yes, and for those serious about weights, I would highly recommend a refurbished Mettler unit similar to this one: http://tinyurl.com/3dz8udc -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: Michael Farmer [mailto:m...@meteoriteguy.com] Sent: Thursday, June 30, 2011 4:55 PM To: Mike Bandli Cc: Michael Gilmer; Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary I use a multi-thousand dollar scale, you are right about the cheap scales, have bought several for the field, they are worthless. Wanna sell the small stuff, make the investment to do it right. Michael Farmer Sent from my iPad On Jun 30, 2011, at 4:52 PM, Mike Bandli fuzzf...@comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg, you need a machine that has been recently leveled and calibrated in-situ. I have a recently leveled/calibrated mechanical scale whose tare changes by the hour due to changes in the weather. It even picks up the subtle vibration of the dishwasher downstairs. Bottom line - a $100 mg scale isn't going to get you the accuracy needed to accurately measure true mg. Since most people can't afford the hundreds to thousands it costs for an accurate mg scale, I don't expect most mg weights advertised to be truly accurate. They're close... Just my 2 mg worth (+/- 1mg)... -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765
Re: [meteorite-list] Micromounts and weights - Standards Vary
PS, Just for fun, If anyone asks you how much you weigh on the Moon, tell them 20 milligrams. At least if you are a 100 kg person (10 mg featherwe...bessyweight for a 50 kg person), if I haven't forgotten to square something somewhere. For the sinister sellers on eBay who wait to weigh their micros when the Moon directly underhead, their 100 kg specimens can be up to 41 mg heavier by pulling that trick! Best wishes -Original Message- From: MexicoDoug mexicod...@aim.com To: vs.petrov...@gmail.com; Meteorite-list@meteoritecentral.com Sent: Fri, Jul 1, 2011 6:43 pm Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary If you measuring such a small thing on the same kind of spring scale at the sea level and at 500m above the sea level, the scale will show you a different result. Simple example: Hi Sergey, I think you want to clarify that. If you try to measure something that weighs 0.001 grams ( 1 mg ) at sea level vs. 500 meters higher, it will weigh 251 ng (nanograms) less, but still 1.000 mg = 0.99975 mg. That is not detectable by any conventional scale and other external factors like differences in air density, air saturation, convection, not to mention people walking around nearby, etc. will swamp the difference, not to mention the porosity of the sample itself which is a problem for even the regular fare. But - I think you meant trying to weigh something with the precision of 1 mg for macro sized samples is very difficult. In the case of a ten gram sample the 251 nanograms becomes 2.5 milligrams of difference, and you are right! Kindest wishes Doug -Original Message- From: Sergey Vasiliev vs.petrov...@gmail.com To: Michael Blood mlbl...@cox.net; Met. Mike Bandli fuzzf...@comcast.net; 'Michael Farmer' m...@meteoriteguy.com Cc: Meteorite List meteorite-list@meteoritecentral.com Sent: Fri, Jul 1, 2011 5:24 pm Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Hi All, Actually I always thought that trying to measure something like 0.001g is very difficult. If you measuring such a small thing on the same kind of spring scale at the sea level and at 500m above the sea level, the scale will show you a different result. Simple example: http://www.edinformatics.com/math_science/mass_weight.htm Best, Sergey -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com]On Behalf Of Michael Blood Sent: Friday, July 01, 2011 11:03 PM To: Met. Mike Bandli; 'Michael Farmer' Cc: Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Mike, I checked this out and was confused. The first statement: METTLER TOLEDO AT261 0.01mg Counting Scale in HardCase Implies accuracy down to a tenth of one mg! That is .0001g HOWEVER, the first part of the description reads: Weighing Capacity:205g Repeatability:(0-50g)+/-0.015mg Linearity:(10g)+/-0.03mg Stabilization:(typical)8-12sec What the h*** does that mean? It sounds like a maximum Capacity of 205g, but repeatability:(0-50g)+/- 0.015 seams Like it is saying it can be off by 15mg! THEN: Linearity:(10)+/- 0.03mg Stabilization... sounds Like they are saying it could be off by 30mg. How do others read this? Michael On 6/30/11 5:11 PM, Met. Mike Bandli fuzzf...@comcast.net wrote: Yes, and for those serious about weights, I would highly recommend a refurbished Mettler unit similar to this one: http://tinyurl.com/3dz8udc -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: Michael Farmer [mailto:m...@meteoriteguy.com] Sent: Thursday, June 30, 2011 4:55 PM To: Mike Bandli Cc: Michael Gilmer; Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary I use a multi-thousand dollar scale, you are right about the cheap scales, have bought several for the field, they are worthless. Wanna sell the small stuff, make the investment to do it right. Michael Farmer Sent from my iPad On Jun 30, 2011, at 4:52 PM, Mike Bandli fuzzf...@comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg,
Re: [meteorite-list] Micromounts and weights - Standards Vary
Hi List, As a non-dealer, but the ocassional passer-on-of-specimens, (normally the ocassional SA batches or other noteables), I use an x.xx scale yet have always quoted the weight to x.x -(.x) ...with respect to my error potential. Quoting at least a -.x (i.e. 68.8gr instead of the scale's reading of 68.9 or 68.92) to at least insure satisfaction, I don't expect anyone to get PO-ed when it weighs more than quoted. Yet this does invite an inaccuracy element with regard to my labels. I'd love to hear some feedback here, so please chime in. For the specimens with a stellar provenence chain-of-custody, I still check and adjust. Crumbs can fall... Or, the original seller may have weighed the specimen from 30K feet :) -Richard Montgomery - Original Message - From: Michael Blood mlbl...@cox.net To: Met. Mike Bandli fuzzf...@comcast.net; Met. Michael Gilmer meteoritem...@gmail.com; Meteorite List meteorite-list@meteoritecentral.com Sent: Friday, July 01, 2011 1:37 PM Subject: spam: Re: [meteorite-list] Micromounts and weights - Standards Vary Hi Mike and all, I absolutely agree. I used to use a $500 digital and now Use a $135 digital and I consider them both about as accurate As the other ~ deduct one decimal point for absolute accuracy. (it is likely far closer than that, but one should not proclaim a specific weight, IE .007g (7mg) unless one has a serious balance beam in an air tight setup. A royal pain in the a** And extremely costly. However, for the most part, I always sell micromounts - the Ones less than 10mg, based on VISUAL COMPARISON. That is What I look for for my own collection... If I want something that Is so small, then the size is far more important to me than the mass. BTW, a micromount has traditionally been defined as any Specimen that fits into an old style 1 X 1 square display box. The new, vastly superior membrane boxes are considerably larger And can hold a decent sized macromount equally well as a micromount. Best regards, Michael On 6/30/11 4:52 PM, Met. Mike Bandli fuzzf...@comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg, you need a machine that has been recently leveled and calibrated in-situ. I have a recently leveled/calibrated mechanical scale whose tare changes by the hour due to changes in the weather. It even picks up the subtle vibration of the dishwasher downstairs. Bottom line - a $100 mg scale isn't going to get you the accuracy needed to accurately measure true mg. Since most people can't afford the hundreds to thousands it costs for an accurate mg scale, I don't expect most mg weights advertised to be truly accurate. They're close... Just my 2 mg worth (+/- 1mg)... -- Mike Bandli Historic Meteorites www.HistoricMeteorites.com and join us on Facebook: www.facebook.com/Meteorites1 IMCA #5765 --- -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] On Behalf Of Michael Gilmer Sent: Thursday, June 30, 2011 4:17 PM To: Meteorite List Subject: [meteorite-list] Micromounts and weights - Standards Vary Hi Listees and Micronauts, There has been some discussion recently about people buying micromounts from a vendor on eBay and not getting the weights they were promised. I thought I would throw out some thoughts on micros, since those are my bread and butter. First, the definition of micromount is relative. There is no set-in-stone size bracket for what defines a micromount. It seems to me that the general consensus is that micromounts are in the 1g range for the more common types and sub-gram in weight for the rare types. Very rare falls or planetaries are commonly sold by the milligram. Rockhounds tend to equate meteorite micromounts with mineral thumbnails. But generally speaking, most micromounts on the market today are in the sub-gram (1g) range. Ideally, a micromount should be visually appealing (such a well polished, thin part slice with good surface area to weight ratio) and big enough to identify the lithology of the type/fall, while at the same time being cheap enough to afford on a limited budget. The more preparation that goes into making a given micromount, the higher the price, generally speaking. At some point, it's not financially viable to put a lot of cutting and
[meteorite-list] ad/sale HUGE Canyon Diablo graphite full slice!
Hi all you will likely never get another shot at a Graphite slice this large, this solid and this BEAUTIFUL! Really it is gorgeous and my very last one for sale. The remaining mass is locked away in a university collection and gone from our reach forever. You can see the piece here first come first served. Free world wide shipping if you mention this ad.http://www.meteoritefinder.com/whats-new-sale.htm -- Mike Miller 3835 E Nicole Ave Kingman Az 86409 www.meteoritefinder.com 928-757-1378 __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Micromounts and weights - Standards Vary
Just to clarify a bit - there is a difference between precision and accuracy. If the finest division on a scale is 0.1 mg, this is an indication of the precision of the scale - how repeatable the measurement is. You could weigh a specimen several times on the scale and get close agreement of the measurements to the 0.1 mg limit to which the scale reads. However, this is not tied to the accuracy of the scale, which might be expressed as a percent for a particular weight range (e.g. 5% for the 0 to 10 gram range). So you can weigh a specimen several times to the nearest 0.1 mg and get results that agree very well (good precision), but the results could be highly inaccurate. It's similar to using a ruler that was incorrectly manufactured so that it is actually 13 inches instead of 12 inches. Every time you measure a length, you come up with 12.0 inches, so the measurements are very precise, but highly inaccurate, because you really measured 13.0 inches. So the accuracy has to do with the calibration of the scale, thermal conditions, etc. Having a scale that reads to the 0.001 mg gives no guarantee at all that the readings are accurate to 0.001 mg, or for that matter anywhere close. You need to check the specs of the scale for the accuracy. Mark Mark Grossman Meteorite Manuscripts - Original Message - From: Richard Montgomery rickm...@earthlink.net To: Michael Blood mlbl...@cox.net; Met. Mike Bandli fuzzf...@comcast.net; Met. Michael Gilmer meteoritem...@gmail.com; Meteorite List meteorite-list@meteoritecentral.com Sent: Friday, July 01, 2011 7:53 PM Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Hi List, As a non-dealer, but the ocassional passer-on-of-specimens, (normally the ocassional SA batches or other noteables), I use an x.xx scale yet have always quoted the weight to x.x -(.x) ...with respect to my error potential. Quoting at least a -.x (i.e. 68.8gr instead of the scale's reading of 68.9 or 68.92) to at least insure satisfaction, I don't expect anyone to get PO-ed when it weighs more than quoted. Yet this does invite an inaccuracy element with regard to my labels. I'd love to hear some feedback here, so please chime in. For the specimens with a stellar provenence chain-of-custody, I still check and adjust. Crumbs can fall... Or, the original seller may have weighed the specimen from 30K feet :) -Richard Montgomery - Original Message - From: Michael Blood mlbl...@cox.net To: Met. Mike Bandli fuzzf...@comcast.net; Met. Michael Gilmer meteoritem...@gmail.com; Meteorite List meteorite-list@meteoritecentral.com Sent: Friday, July 01, 2011 1:37 PM Subject: spam: Re: [meteorite-list] Micromounts and weights - Standards Vary Hi Mike and all, I absolutely agree. I used to use a $500 digital and now Use a $135 digital and I consider them both about as accurate As the other ~ deduct one decimal point for absolute accuracy. (it is likely far closer than that, but one should not proclaim a specific weight, IE .007g (7mg) unless one has a serious balance beam in an air tight setup. A royal pain in the a** And extremely costly. However, for the most part, I always sell micromounts - the Ones less than 10mg, based on VISUAL COMPARISON. That is What I look for for my own collection... If I want something that Is so small, then the size is far more important to me than the mass. BTW, a micromount has traditionally been defined as any Specimen that fits into an old style 1 X 1 square display box. The new, vastly superior membrane boxes are considerably larger And can hold a decent sized macromount equally well as a micromount. Best regards, Michael On 6/30/11 4:52 PM, Met. Mike Bandli fuzzf...@comcast.net wrote: A little perspective on milligrams: There are a lot of meteorite mg weights out there that not accurate. We can thank these new, cheap Chinese digital scales that promise accuracies of +/- 1mg or less, which are a complete joke. I bought one in Tucson to test it out against my high-end calibrated machine and it was off by about 10 mg on average for pieces 50 to 100 mg and 5 mg on average for pieces 10 to 50 mg. Anything fewer than 10 mg - forget about it. The calibration weights it came with were even more laughable... In reality, in order to be able to accurately measure mg, you need a machine that has been recently leveled and calibrated in-situ. I have a recently leveled/calibrated mechanical scale whose tare changes by the hour due to changes in the weather. It even picks up the subtle vibration of the dishwasher downstairs. Bottom line - a $100 mg scale isn't going to get you the accuracy needed to accurately measure true mg. Since most people can't afford the hundreds to thousands it costs for an accurate mg scale, I don't expect most mg weights advertised to be truly accurate. They're close... Just my 2 mg worth (+/- 1mg)...
Re: [meteorite-list] Micromounts and weights - Standards Vary
The 20 milligram weight would be the weight of a 100 kg person if they were freely floating in space at a one Earth-Moon distance from the Moon. But, and a big but - but because the Earth is 'supporting' them when the Moon is overhead, although the Moon would pull them and lighten the apparent weight, it also pulls the Earth under which 'pushes' up against them increasing the weight that same 20 milligrams to offset the weight difference. I.e, when you are on the surface of a mass coupled to another body through gravitation, the only body that matters is the one you are on. The apparent gravitational pull of the distant object is not measurable. My bad. So this is not a variable that affects the measured weight on the scales. They are not affected by the Sun and Moon, to a first approximation (though there is a curious tiny difference for a different reason). Lucky, because if this were not the case the Sun would cause a +/- two ounce weight difference for the same reason for the 100 kg mass person; the two ounces corresponds to their weight if they were freely floating at 1 AU from the Sun. I thunk. Best wishes Doug -Original Message- From: MexicoDoug mexicod...@aim.com To: vs.petrov...@gmail.com; Meteorite-list@meteoritecentral.com Sent: Fri, Jul 1, 2011 7:28 pm Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary PS, Just for fun, If anyone asks you how much you weigh on the Moon, tell them 20 milligrams. At least if you are a 100 kg person (10 mg featherwe...bessyweight for a 50 kg person), if I haven't forgotten to square something somewhere. For the sinister sellers on eBay who wait to weigh their micros when the Moon directly underhead, their 100 kg specimens can be up to 41 mg heavier by pulling that trick! Best wishes -Original Message- From: MexicoDoug mexicod...@aim.com To: vs.petrov...@gmail.com; Meteorite-list@meteoritecentral.com Sent: Fri, Jul 1, 2011 6:43 pm Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary If you measuring such a small thing on the same kind of spring scale at the sea level and at 500m above the sea level, the scale will show you a different result. Simple example: Hi Sergey, I think you want to clarify that. If you try to measure something that weighs 0.001 grams ( 1 mg ) at sea level vs. 500 meters higher, it will weigh 251 ng (nanograms) less, but still 1.000 mg = 0.99975 mg. That is not detectable by any conventional scale and other external factors like differences in air density, air saturation, convection, not to mention people walking around nearby, etc. will swamp the difference, not to mention the porosity of the sample itself which is a problem for even the regular fare. But - I think you meant trying to weigh something with the precision of 1 mg for macro sized samples is very difficult. In the case of a ten gram sample the 251 nanograms becomes 2.5 milligrams of difference, and you are right! Kindest wishes Doug -Original Message- From: Sergey Vasiliev vs.petrov...@gmail.com To: Michael Blood mlbl...@cox.net; Met. Mike Bandli fuzzf...@comcast.net; 'Michael Farmer' m...@meteoriteguy.com Cc: Meteorite List meteorite-list@meteoritecentral.com Sent: Fri, Jul 1, 2011 5:24 pm Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Hi All, Actually I always thought that trying to measure something like 0.001g is very difficult. If you measuring such a small thing on the same kind of spring scale at the sea level and at 500m above the sea level, the scale will show you a different result. Simple example: http://www.edinformatics.com/math_science/mass_weight.htm Best, Sergey -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com]On Behalf Of Michael Blood Sent: Friday, July 01, 2011 11:03 PM To: Met. Mike Bandli; 'Michael Farmer' Cc: Meteorite List Subject: Re: [meteorite-list] Micromounts and weights - Standards Vary Mike, I checked this out and was confused. The first statement: METTLER TOLEDO AT261 0.01mg Counting Scale in HardCase Implies accuracy down to a tenth of one mg! That is .0001g HOWEVER, the first part of the description reads: Weighing Capacity:205g Repeatability:(0-50g)+/-0.015mg Linearity:(10g)+/-0.03mg Stabilization:(typical)8-12sec What the h*** does that mean? It sounds like a maximum Capacity of 205g, but repeatability:(0-50g)+/- 0.015 seams Like it is saying it can be off by 15mg! THEN: Linearity:(10)+/- 0.03mg Stabilization... sounds Like they are saying it could be off by 30mg. How do others read this? Michael On 6/30/11 5:11 PM, Met. Mike Bandli fuzzf...@comcast.net wrote: Yes, and for those serious about weights, I would highly recommend a refurbished Mettler unit similar to
