Good Question- Other things to consider are the type of variogram and the total sill. My PERSONAL opinions include the following (using a completely different tack)): 1.For measured resources no additional exploration type sampling should be required. Additional sampling and drilling for breakage and ore control is okay. 2.For measured, reconciliation over a quarter should be within plus or -10% in terms of tons, grade and contained metal 95% of the time. 3.For measured and indicated, reconciliation over a year should be within plus or -10% in terms of tons, grade and contained metal 95% of the time. 4.For measured and indicated, reconciliation over life of mine should be within plus or -10% in terms of tons, grade and contained metal 95% of the time. 5.It is acceptable to use plus or -15% instead of plus or -10 as this is a usual standard of accuracy for a feasibility study. 6.The plus or -10% should be reduced if the -10% case is uneconomic. (If you have to reduce the standard of accuracy to maintain an economic project. the project is probably not a good idea). There are several objections to the above criteria: 1. Three and four are probably statistically inconsistent. 2. Measured and indicated are dependent on mining rate. It is generally possible, once your criteria (two, three and four) are selected to translate this into a distance and number of holes and composites criteria.
Regards Robert (Bob) L. Sandefur PE Senior Geostatistician / Reserve Analyst CAM 12600 West Colfax Suite A-250 Lakewood, Co 80215 rsande...@cam-llc.com 303 472-3240 (cell) <-best choice 303 716-1617 ext 14 The content of this message may contain the private views and opinions of the sender and does not constitute a formal view and/or opinion of the company unless specifically stated. The contents of this email and any attachments may contain confidential and/or proprietary information, and is intended only for the person/entity to whom it was originally intended. Any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this email in error please notify the sender immediately by return e-mail and delete this message and any attachments from your system. -----Original Message----- From: gregoire.dub...@gmail.com [mailto:gregoire.dub...@gmail.com] On Behalf Of M. Nur Heriawan Sent: Monday, November 01, 2010 18:55 To: ai-geostats@jrc.it Subject: AI-GEOSTATS: nugget ratio vs. range of variogram Dear list, Some people used the range of variogram to optimize the drillhole spacing and radius of resource classification of a deposit. But as we knew that the nugget ratio (nugget variance/total sill) of variogram could vary to be low (<25%), medium (25-50%), high (50-75%), and extremely high (>75%). So how can we define the correct range related to the such types of nugget ratio? In my opinion when the nugget ratio is low, then our variogram range is robust, but how for the others? When the nugget ratio is extremely high, then the range is almost none. Is there a mathematical relationship between nugget effect or nugget ratio with the range of variogram? Looking forward to the suggestions and references from the list. Thank you for attention. Best regards, --------------- M. Nur Heriawan Earth Resources Exploration Research Group Faculty of Mining and Petroleum Engineering Institut Teknologi Bandung (ITB) Jl. Ganesha 10 Bandung 40132 INDONESIA http://www.mining.itb.ac.id/heriawan + + To post a message to the list, send it to ai-geost...@jrc.ec.europa.eu + To unsubscribe, send email to majordomo@ jrc.ec.europa.eu with no subject and "unsubscribe ai-geostats" in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list + As a general service to list users, please remember to post a summary of any useful responses to your questions. + Support to the forum can be found at http://www.ai-geostats.org/ + + To post a message to the list, send it to ai-geost...@jrc.ec.europa.eu + To unsubscribe, send email to majordomo@ jrc.ec.europa.eu with no subject and "unsubscribe ai-geostats" in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list + As a general service to list users, please remember to post a summary of any useful responses to your questions. + Support to the forum can be found at http://www.ai-geostats.org/
