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Mine sampling and valuing; a discussion of the methods used in sampling and valuing ore deposits, with especial reference to the work of valuation by the independent engineer
by:Charles Simon Herzig
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 Excerpt: ...the illustration just given, in each component the quantity was multiplied by the assay which gave a factor in this case the total gold which added...
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 Excerpt: ...the illustration just given, in each component the quantity was multiplied by the assay which gave a factor in this case the total gold which added together with the other factor arrived at in the same way and divided by the total quantity gave the average assay value. In averaging mine samples, as the tonnage is directly proportional to the width sampled, the width is used instead of tonnage. The mathematics governing this method is fully discussed both in H. C. Hoover's1 and T. A. Rickard's2 books and no good purpose is to be served by repeating it here. That the arithmetrical average gives an incorrect result has been demonstrated by the two problems already given. To get the volumetric average, the following is the general method employed. The assay value for each metal is multiplied by the sample width in inches. This gives an arbitrary factor called the inch-shilling, inchdollar, inch-pennyweight, or inch-per-cent, as the case may be. The sum of these for the samples to be averaged, divided by the sum of the widths sampled, gives the average assay value of the lot. Americans generally measure widths in feet and decimals, in which case the footdollar, or foot-per cent is used as a factor. Referring to Diagram /, sample No. 101 is a simple case where the two fractions will be mined together. To get the average, multiply 14 (width of 101) by $7.50 (total gold and silver value) which gives 105 inch-dollars, to which must be added 46 (width of 101H) multiplied by $19.00 (total gold and silver value of same) or 874 inch-dollars, giving a total of 979 inch-dollars. Divide this by 60, the total width (the sum of 14+46), and there results a quotient of 163.27, which is the average value of the whole interval for the total width of 60 inches. Looking at the res...
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