Re: [meteorite-list] Whites dfx good for meteorte hunting??
-Original Message- >From: Count Deiro >Sent: Oct 24, 2010 8:51 PM >To: Meteorites USA , >meteorite-list@meteoritecentral.com >Subject: Re: [meteorite-list] Whites dfx good for meteorte hunting?? > >Hi Eric, > >Don't want to mislead you. I am no expert.. and only recently began using a >detector for meteorites. I used to have a Whites that I used for coin and >relic shooting, but I didn't like the weight and handling qualities. You'll >find that middle of the line (less than $1,000) detectors made by Fishers, >Whites and MineLab all work equally well on locating meteorites...so the next >most important thing would be weight and ease of use because you'll be >swinging the thing for hours at a time. I found the Minelab 705 unit with >digital circuitry and both manual and auto ground balance to be the best for >me. It is the lightest and evenly balanced unit on the market. It's like >holding nothing in your hand when you set the length of the shaft for your >height. The standard Vtech and slipper coils that usually come with it work >very well to depths of two to three feet in the desert pavement and sandy >soils of Nevada. Most of what I detect is on the surface and picked up in the >all metal mode with tracking auto balance. You can really cover ground without >tiring and it is cheap to operate using only two AA batteries every couple of >days. The unit is as sophisticated as the big buck detectors and has multiple >preprogrammed-programmed detection and discrimination modes. Used 705s can be >had for around $500.00. > >If you were looking to go deep you'd be better off constructing your own sled >mounted coil and haul it with an ATV. I am designing such a rig for use on dry >lakes and level areas and will use the head from the MineLab 705 I have now. > >I really can't see spending thousands for a detector to hunt meteorites. You >don't usually find them around trashy, electrically noisy areas, so why blow >dough on a heavy duty ground pounder. > >Good luck, > >Count Deiro >IMCA 3536 > > >-Original Message- >>From: Meteorites USA >>Sent: Oct 24, 2010 4:34 PM >>To: meteorite-list@meteoritecentral.com >>Subject: Re: [meteorite-list] Whites dfx good for meteorte hunting?? >> >>Hi Andre, Not sure about the DFX. Never used it. The GMT is good, I've >>heard many good reviews from meteorite hunters saying it's a great >>detector. Also the Fisher Gold Bug, and Gold Bug 2 and White's VSAT. >>These are detectors I've found meteorites with.. They work well. >> >>Eric >> >> >>On 10/24/2010 12:08 PM, André Moutinho wrote: >>> Hello, is this a good detector for meteorite hunting? Any other good >>> alternative? >>> I already use a Whites goldmaster gmt but would like to get a better one >>> with bigger coil. >>> The cost to replace the GMT lead me to think in another detector. >>> >>> Thanks >>> Andre >>> __ >>> 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 >>> >>> >>__ >>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 > >__ >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 __ 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] Apology last post on detectors.
Sorry Eric and List, My last was directed to Andre...not you Eric. You've forgotten more than I know about detectors. Regards, Guido __ 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] Whites dfx good for meteorte hunting??
Hi Eric, Don't want to mislead you. I am no expert.. and only recently began using a detector for meteorites. I used to have a Whites that I used for coin and relic shooting, but I didn't like the weight and handling qualities. You'll find that middle of the line (less than $1,000) detectors made by Fishers, Whites and MineLab all work equally well on locating meteorites...so the next most important thing would be weight and ease of use because you'll be swinging the thing for hours at a time. I found the Minelab 705 unit with digital circuitry and both manual and auto ground balance to be the best for me. It is the lightest and evenly balanced unit on the market. It's like holding nothing in your hand when you set the length of the shaft for your height. The standard Vtech and slipper coils that usually come with it work very well to depths of two to three feet in the desert pavement and sandy soils of Nevada. Most of what I detect is on the surface and picked up in the all metal mode with tracking auto balance. You can really cover ground without tiring and it is cheap to operate using only two AA batteries every couple of days. The unit is as sophisticated as the big buck detectors and has multiple preprogrammed-programmed detection and discrimination modes. Used 705s can be had for around $500.00. If you were looking to go deep you'd be better off constructing your own sled mounted coil and haul it with an ATV. I am designing such a rig for use on dry lakes and level areas and will use the head from the MineLab 705 I have now. I really can't see spending thousands for a detector to hunt meteorites. You don't usually find them around trashy, electrically noisy areas, so why blow dough on a heavy duty ground pounder. Good luck, Count Deiro IMCA 3536 -Original Message- >From: Meteorites USA >Sent: Oct 24, 2010 4:34 PM >To: meteorite-list@meteoritecentral.com >Subject: Re: [meteorite-list] Whites dfx good for meteorte hunting?? > >Hi Andre, Not sure about the DFX. Never used it. The GMT is good, I've >heard many good reviews from meteorite hunters saying it's a great >detector. Also the Fisher Gold Bug, and Gold Bug 2 and White's VSAT. >These are detectors I've found meteorites with.. They work well. > >Eric > > >On 10/24/2010 12:08 PM, André Moutinho wrote: >> Hello, is this a good detector for meteorite hunting? Any other good >> alternative? >> I already use a Whites goldmaster gmt but would like to get a better one >> with bigger coil. >> The cost to replace the GMT lead me to think in another detector. >> >> Thanks >> Andre >> __ >> 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 >> >> >__ >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 __ 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] Whites dfx good for meteorte hunting??
Hi Andre, Not sure about the DFX. Never used it. The GMT is good, I've heard many good reviews from meteorite hunters saying it's a great detector. Also the Fisher Gold Bug, and Gold Bug 2 and White's VSAT. These are detectors I've found meteorites with.. They work well. Eric On 10/24/2010 12:08 PM, André Moutinho wrote: Hello, is this a good detector for meteorite hunting? Any other good alternative? I already use a Whites goldmaster gmt but would like to get a better one with bigger coil. The cost to replace the GMT lead me to think in another detector. Thanks Andre __ 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 __ 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] AD- Ebay - Sikhote-Alin 435g Stunning Individual!!
Hi everyone, hope you all had a great weekend. I just listed a nice Sikhote-Alin 435g on ebay. Very nice looking example. Go take a look! Hasta luego, http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130447766799#ht_500wt_1156 -- Felipe __ 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] metachondrite
I don't think it's appropriate to say that somebody who does not like a term suggested in a couple of abstracts is a "purist who sh[ies] away from any thinking out of the conventional box"! As far as I understand the term, there do not seem to be any concepts behind "metachondrite" that are outside the boxes of the existing terminology. It just appears to me to be a new word for something we already have terms to describe. So it comes down to a question of semantics. "Type 7" chondrites have not been "excommunicated" either. It has been a problematic term because some of the rocks that led to the coining of this term turned out to be impact melt rocks, which is a different phenomenon from the thermal metamorphism we are trying to describe with petrologic types. Once you take these out, there are a few rocks that arguably are metamorphosed to slightly higher temperatures than normal type 6 chondrites, with the primary indicator of this being high CaO content of pyroxene. I have no strong objection to these being called type 7, although I'm not convinced that the term is particularly necessary. Still, if we're sure we're not dealing with impact melted rocks or rocks that have experienced partial melting, then I think the term is ok. That's why some of these got through the nomcom. Once again, this is not an "outside the box" term, just a minor extension of the usual classification scheme (when used carefully). And finally, as I said before, the word "primitive" in PAC refers to the composition, which is close to chondritic compared to, say, that of a eucrite, aubrite, or angrite. The same word is frequently used by geologists to describe the Earth's mantle before it gets depleted in certain elements by generation of melts. The word is perfectly fine in this context. Jeff On 2010-10-24 4:20 PM, Ted Bunch wrote: Jeff and the LIST members: Yes, Van Schmus and Wood (V & W) did a classic study over 40 years ago, they worked with the available classic OC meteorites and made a workable classification scheme. That was 43 years ago and things change, especially the 10s of thousands of non-classic meteorites available for study and advanced instrumentation including the now common usage of SEM BSE imagery and elemental distribution mapping. V & W probably never saw a completely recrystallized OC, they are not even common now. Investigators started seeing OCs that had absolutely NO relict chondrules or chondrule fragments. So, apparently, the V & W scheme became inadequate over time and the "petrologic" classification scheme was unofficially amended with L7, LL7, H7, etc. Seemed reasonable to us. But, not to the purists who shy away from any thinking out of the conventional box. "Sevens" were excommunicated, a few got through a couple of NOM COMs. Because "sevens" are completely recrystallized with some elemental loss, we thought that metachondrite was appropriate, but not until our paper on metachondrites goes through the peer review process - if you are clever handicappers, don't bet on this horse. I think we have the same chance as did Joan of Arc with her Inquisition. Metamorphism of chondrites took place over hundreds of thousands of years at elevated temperatures and not necessarily under closed systems. With this concept in mind -- What is a "primitive achondrite"? Actually, they are metamorphosed/recrystallized rocks that are not the same, even compositionally, as their parent rocks. Primitive? I think not. One dictionary definition of primitive is “not derived from other things”. Acapulcoites and lodranites _are derived from other things, hence not primitive. _A primitive meteorite to me means a CI or may be a CM1, although even these types sustained aqueous alteration. However, Orgueil, even with aqueous alteration, appears to have retained its elemental solar abundances. Because of the huge number of meteorites that have been discovered over the last 20 years, it is time to re-invent other classification schemes for other meteorite classes, namely Martians, in addition to OCs and “primitives”. A recent paper in MAPs has suggested a new scheme for diogenites. We need to get our heads out of the sand box and address these issues. Moreover, in a few years, the few members of the “ungrouped “ meteorites will probably reach the necessary quota of 5 or more to be eligible for a new class. Motivation and patience will prevail, Ted Ted Bunch On 10/24/10 8:45 AM, "Jeff Grossman" wrote: > Here is the opposing view: > > The definition of type 6 chondrites comes from one of the classic papers > in meteoritics, Van Schmus and Wood (1967): "As mentioned above, type 6 > contains the most recrystallized chondrites. These chondrites show > extensive-to-complete obliteration of the primary textures (Fig. 11), > extensive evidence of recrystallization of the original olivine and > pyroxene crystals, and good-to-excellent development of pl
[meteorite-list] Whites dfx good for meteorte hunting??
Hello, is this a good detector for meteorite hunting? Any other good alternative? I already use a Whites goldmaster gmt but would like to get a better one with bigger coil. The cost to replace the GMT lead me to think in another detector. Thanks Andre __ 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] metachondrite
Hello Jeff, we tried this time more to explain, what these stones are and not so the terminology, because to some list-members it seemed unclear, what these metachondrites/PACs/7ers are and how they formed. How they shall be called, we leave to each one individually (cause it doesn't change the stones). But Jeff note, that at least the term chondrite vs. achondrite shouldn't be too dogmatically handled, if you remember, that there is also a class formally reckoned among the chondrites, although it hasn't any chondrules, the CI-chondrites - which, if one would be in that sense consequent, would then belong nominally also in the PAC-pot, wouldn't they? For us at least, the metachondrite-terminology would have some advantages. If we read L-metachondrite, LL-metchondrite, CR-metachondrite, we simply know, what the stone IS. An L-metachondrite - everybody knows immediately, aha, precursor material was an L-chondrite, that stone belongs into the L-group. With "PAC"? PAC can be everything. And if we open a pot labeled "PAC" - then we lump together meteorites from many different parent bodies. That would be unique in the nomenclature and inconsistent. Because no class/denomination there, under which you have meteorites from different parent bodies. Traditionally you have in a group only stones from more or the less of one kind, from one parent body, and they were named according the first find/fall described. Aubrites from Aubres, Acapulcoites from Acapulco, Brachinites from Brachina, Shergottites from Shergotty...and so on (and we were lucky, that none of the namesake was from Poland, Święcanites, ostrzeszówites... ) - or which were historically named like the eucrites, diogenites, howardites, or where the relations were understood, then at least with the initial from the 1st find/fall. CI from Ivuna, CV from Vigarano, CK from Karoonda ect. With that metamorph chondrites it doesn't work. Simply because they are not a class of their own, they clearly belong into the existing groups. To the Hs, to the Ls, to the CVs ect. (so "ungrouped" they are in no case). If you would call them "7", then we wouldn't haven't a problem. And of course, one could also pack everything, which has a relic chondrule left, to the 6ers. But to throw all those, which haven't, into the unspecific PAC - creating almost a pseudo-class or -group, would mean an unnecessary coarsening. Also we don't know then the hierarchic structure of the terminology of the classification scheme so well. Would we have then these main groups with these hypernyms:Chondrites, Achondrites (from differentiated parent bodies), Irons, Primitive Achondrites? If so, or also in general, wouldn't it be then anyway necessary to preserve the L-metachondrites, H-metachondrites, LL-meta... as subgroups of the PACs, because we have so heterogeneous meteorites in that group then? Or could one then create rather something like a L-PAC, H-PAC, CV-PAC - (huh ACAPPAC sounds cool). Hmmm, would be much more elegant, to put the PACs (as long as we don't know so much about the precursors of the ACAP/LODs and the WINs) simply as subgroup to the achondrites and the Meta7PACs, there where they generically and chemically belong to, to the individual chondrite classes as metachondrites. If that's feasible at all. Thoughts only, Martin & Stefan -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Jeff Grossman Gesendet: Sonntag, 24. Oktober 2010 17:45 An: meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] metachondrite Here is the opposing view: The definition of type 6 chondrites comes from one of the classic papers in meteoritics, Van Schmus and Wood (1967): "As mentioned above, type 6 contains the most recrystallized chondrites. These chondrites show extensive-to-complete obliteration of the primary textures (Fig. 11), extensive evidence of recrystallization of the original olivine and pyroxene crystals, and good-to-excellent development of plagioclase..." Note that this definition includes chondrites that are so recrystallized that chondrules are no longer recognizable. A number of us petrologists think that most "type 7" chondrites fit comfortably within this definition of type 6, and consider the former term to be superfluous. With continued heating, chondrites eventually begin to partially melt (reaching the Fe-FeS eutectic temperature and eventually the point where a feldspathic silicate liquid can form). At this point, differentiation can begin, as these liquids separate from residual solids. When some differentiation occurs, it can produce rocks that are nearly chondritic in composition, but depleted in elements that went into these liquids. That is the definition of "primitive achondrite": "primitive" refers to the composition, which is still close to chondritic, and "achondrite" refers to the lack of chondrules,
[meteorite-list] Finding fossil Meteorites
Hi List, Has anyone read this great artical about meteorites being found in Ordivician fossil limestone. After reading it I starting searching months ago. And found 2 very interesting stones, One looks like it could be a diogenite and the other stone has a subophitic texture like some lunars and a few Angrites So here is a link to the artical if you have not read it, http://www.psrd.hawaii.edu/Mar04/fossilMeteorites.html and second is link is to my face book page with pictures of what I found and where they were found, Just wondering are they worth getting tested, I do not want to waste money if there not. Thanks for any info. http://www.facebook.com/#!/album.php?aid=47781&id=10209843157 __ 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] AD Atomic Bomb pics
Hi Carl and List, Those atom bomb pictures are really cool. One of those (or several) would look great as part of a trinitite display. (speaking of which, I have some trinitite available if anyone wants it!):) Best regards, MikeG -- Mike Gilmer - Galactic Stone & Ironworks Meteorites Website - http://www.galactic-stone.com Facebook - http://www.facebook.com/galacticstone 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 10/24/10, cdtuc...@cox.net wrote: > List, > Please check out my ebay listings ending this evening. > of note are a few off topic Atomic Bomb original Photographs. > Click link; > > http://shop.ebay.com/meteoritemax/m.html?_nkw=&_armrs=1&_from=&_ipg=25 > > Carl > -- > Carl or Debbie Esparza > Meteoritemax > > __ > 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 > __ 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] AD Atomic Bomb pics
List, Please check out my ebay listings ending this evening. of note are a few off topic Atomic Bomb original Photographs. Click link; http://shop.ebay.com/meteoritemax/m.html?_nkw=&_armrs=1&_from=&_ipg=25 Carl -- Carl or Debbie Esparza Meteoritemax __ 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] AD - Meteorites for Sale
Here are some selections from the Stephan collection: Lemmon H543.4 g NWA 1955 H/L 3-4 11.3 g Davy(a) L4 36.7 g NWA 2999 Angrite 2.3 g NWA 1914 HOW 53.6 g Itqiy EH7 4.1 g Willard(a) L6 0.50g Yilmia EL6 1.41 g Winona WIN 3.91g NWA 2932 MES 49.4 g For information on these please e-mail Twink Monrad off-list larrytwinkmon...@comcast.net __ 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] metachondrite
Here is the opposing view: The definition of type 6 chondrites comes from one of the classic papers in meteoritics, Van Schmus and Wood (1967): "As mentioned above, type 6 contains the most recrystallized chondrites. These chondrites show extensive-to-complete obliteration of the primary textures (Fig. 11), extensive evidence of recrystallization of the original olivine and pyroxene crystals, and good-to-excellent development of plagioclase..." Note that this definition includes chondrites that are so recrystallized that chondrules are no longer recognizable. A number of us petrologists think that most "type 7" chondrites fit comfortably within this definition of type 6, and consider the former term to be superfluous. With continued heating, chondrites eventually begin to partially melt (reaching the Fe-FeS eutectic temperature and eventually the point where a feldspathic silicate liquid can form). At this point, differentiation can begin, as these liquids separate from residual solids. When some differentiation occurs, it can produce rocks that are nearly chondritic in composition, but depleted in elements that went into these liquids. That is the definition of "primitive achondrite": "primitive" refers to the composition, which is still close to chondritic, and "achondrite" refers to the lack of chondrules, although rare chondrule outlines sometimes persist. The new term "metachondrite" has not been defined in the formal literature, but it seems to overlap with what I would call the "high end" of type 6 and primitive achondrites. I think Ted Bunch reads this list, so he can chime in if this is not correct. Personally, I see no benefit to this term, as I am comfortable calling those with chondritic compositions "type 6 chondrites," and I am uncomfortable calling those which have differentiated "chondrites," even with the prefix "meta-". Jeff On 2010-10-24 10:16 AM, Chladnis Heirs wrote: Hi Steve, no.. a metachondrite is a chondrite without chondrules :-) The "meta" comes from "metamorph". A metamorphosis means, that a rock is changed in its structure or its composition into a different rock, but remaining in a solid state, while this happens. This change can be caused by different agents, like heat, pressure, liquids or contact with other rocks. Well, with the metachondrites (or 7ers or PACs, where they were/are sorted in too) their chemistry and their isotopes are similar with or the same as the respective chondrite groups. L-metachondrites with L; H-metachondrites with H, LL-...ect. Though - they are free of chondrules. But: they show evidence of recrystallization and in some of these stones of that kind, one finds remainders left and relicts, which once were chondrules. Therefore it's clear, they were once chondrites (of the respective groups H, LL, CV, CR now with NWA 6348 the first one, named to come from the L-group) and they are directly derived from the chondrites. So. With the chondrites, you have always those numbers behind the H, L, ect. - the petrological grade. 3,4,5,6. In the type-3 chondrites, you have the full garden of these funny balls called chondrules, sharply defined sitting in the matrix. If you heat now the affair, the crystal growing will take place, and from the 4, to 5, to the 6ers the chondrules and the matrix are more and more grown together, the chondrules get less sharper defined, they got often also more sparsely. And a second thing happens, the constituents of such a 3er, they are chemically and physically different from each other. But like all in universe, they want to be balanced, they desire an equilibrium. If you heat now such a rock, the ions can roam in the rock. And the constituents start to assimilate to each other or to get in a chemical balance. So the type-3 chondrites are those, which were least heated and are the most unchanged preserved once. Called unequilibrated, while from type 4 on they are called equilibrated. Well. So the chondrites evolve and are more and more changed from type-3 to type 6. But with the new finds from the deserts, we got some rocks, which showed, that type 6 is not the end! That there are also chondrites, which were more heated or were that process continued - so that in the end they had lost all their chondrules, and got the most equilibrated ones and fully recrystallized. Two main heat sources you have for such parent bodies. Heating due impacts, where the kinetic energy of the impactor is relieved in deformation of the target rock and heat. The other one is after the formation of such a celestial body, the radioactive decay of its instable and heavy elements. The larger such a body is, the more of that stuff it has, the hotter it can get - up to the complete melting of the body. And the larger such an body is the longer it can keep the heat - Earth e.g. is large enough, that it was quite still warm down there, where the Chilean miners were sitting. Impacts, you know what happen
Re: [meteorite-list] metachondrite
Hi Steve, no.. a metachondrite is a chondrite without chondrules :-) The "meta" comes from "metamorph". A metamorphosis means, that a rock is changed in its structure or its composition into a different rock, but remaining in a solid state, while this happens. This change can be caused by different agents, like heat, pressure, liquids or contact with other rocks. Well, with the metachondrites (or 7ers or PACs, where they were/are sorted in too) their chemistry and their isotopes are similar with or the same as the respective chondrite groups. L-metachondrites with L; H-metachondrites with H, LL-...ect. Though - they are free of chondrules. But: they show evidence of recrystallization and in some of these stones of that kind, one finds remainders left and relicts, which once were chondrules. Therefore it's clear, they were once chondrites (of the respective groups H, LL, CV, CR now with NWA 6348 the first one, named to come from the L-group) and they are directly derived from the chondrites. So. With the chondrites, you have always those numbers behind the H, L, ect. - the petrological grade. 3,4,5,6. In the type-3 chondrites, you have the full garden of these funny balls called chondrules, sharply defined sitting in the matrix. If you heat now the affair, the crystal growing will take place, and from the 4, to 5, to the 6ers the chondrules and the matrix are more and more grown together, the chondrules get less sharper defined, they got often also more sparsely. And a second thing happens, the constituents of such a 3er, they are chemically and physically different from each other. But like all in universe, they want to be balanced, they desire an equilibrium. If you heat now such a rock, the ions can roam in the rock. And the constituents start to assimilate to each other or to get in a chemical balance. So the type-3 chondrites are those, which were least heated and are the most unchanged preserved once. Called unequilibrated, while from type 4 on they are called equilibrated. Well. So the chondrites evolve and are more and more changed from type-3 to type 6. But with the new finds from the deserts, we got some rocks, which showed, that type 6 is not the end! That there are also chondrites, which were more heated or were that process continued - so that in the end they had lost all their chondrules, and got the most equilibrated ones and fully recrystallized. Two main heat sources you have for such parent bodies. Heating due impacts, where the kinetic energy of the impactor is relieved in deformation of the target rock and heat. The other one is after the formation of such a celestial body, the radioactive decay of its instable and heavy elements. The larger such a body is, the more of that stuff it has, the hotter it can get - up to the complete melting of the body. And the larger such an body is the longer it can keep the heat - Earth e.g. is large enough, that it was quite still warm down there, where the Chilean miners were sitting. Impacts, you know what happens, if the smack is hefty, then the rock beneath simply melts - making these IMB, impact melt breccias meteorites, usually quite black, homogenous and with textureless glasses.. The metachondrites are different from them. If you take that idea with that heating by decay, then you can suppose, that they once sat more deeper, closer to the core of their parent body than the 3ers, 4ers,... where it got hotter and where it was longer hot. Now, cause 6 was obviously not the end, Dodd in the 1970ies thought it is necessary to have also a 7. Problem: Most of these crazy stones have no chondrules left. Therefore some say: A chondrite is called a chondrite because it has chondrules! A stone, that has no chondrules has to be called: achondrite!! Therfore a 7er-chondrite would be per definition not allowed. And because the stuff is directly derived from chondrites, which are the most primitive matter we have, we put these stones into the group, we already have, where the ACAPs, LODs, WINs are already sitting in and call them "primitive achondrites". And that is somewhat unhappy. Achondrites we have all that stuff from differentiated, non-chondritic parent bodies, like the Vesta matters eucrites, diogenites, howardites, but also the aubrites, ureilites, brachinites, angrites, Martians, Lunars... But from these stones, we know exactly from their composition that they were chondrites. And "primitive" doesn't fit so well neither - because they aren't that primitive but among the chondrites the most metamorph, most evolved, most equilibrated ones of all. And they are not an unchanged primary meteorite, they are a product of them. The opposite of "primitive". The term "Metachondrite" is there more exact, it says: Look I was a chondrite - I am a metamorph chondrite. So in the name the genesis of the rock is already visible. And it allows to be more specific, as one hasn't to lump all these rocks, from ACAPs, WINs and all these diverse "ex
[meteorite-list] AD: Trade/Sale webpage update
Dear List members, I added a Sahara 97159 EH3 part slice, an Olivine Diogenite slice and an UNWA to my Trade/Sale webpage. Furthermore, price indication have been added, in case buying is preferred. Have a look at: http://www.AsteroidChippings.com/Trade_sale.html Enjoy, Rob Lenssen IMCA #1681 __ 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
