The labeling is required to identify gold exploration samples. Basically, durable tags carrying the number of the sample should be inserted in each bag; some gold prospectors use metal tags, some wood, but the usual practice is to use tough paper rolled up tightly to prevent abrasion. The following sample tag is excellent, and should be made up in blocks containing 100 sheets and numbered before going into the mine. The lower part of the tag is torn off, and after being rolled up, is inserted in the bag with the sample.
The label must include the following information: Date; Sample taken; At point; From; Across; Measurement: At right angles to dip, vertical, horizontal; Dip Strike; Number of perforation. By tearing the detached slip in half gives two numbers for the duplicates when the sample is cut down. On the backs of these slips the gold prospector is accustomed to make a sketch in section of the place sampled showing the shape of the drift and the sample cut by a dotted line; the geological features may also be indicated with colored pencils; and any remarks noted. The data is thus kept in convenient form for future reference and is invaluable in case of dispute; it frequently happens that an unfavorable report is questioned or disputed, and in any controversy regarding samples these labels so kept will put the adversary to rout on sight.
The prospector writes the sample number on the outside of the bags to permit ready identification without having to pour out the sample in search of the tag. This practice is objected by some prospectors on the ground that it permits an outsider to locate the samples with equal ease. If an outsider gets close enough to the samples, and the leisure in which to inspect the numbers, he is close enough to tamper with them, and this objection is not therefore, considered as having weight.
The size of a sample should be limited to the least amount that will yield a true average of the exposure sampled. A few large samples are of little value as compared with many smaller samples, if the latter be well taken. Car-load shipments, ton-samples, and shooting down large samples are not good methods, as a bunch of rich ore is capable of salting the whole sample, and any sample that is too large to be sealed in a bag and properly protected against salting is a source of danger. Small mill runs are not satisfactory on any but very high-grade ores, as the clean-up will depend largely upon whether the plates are scraped clean. It has been noted that the more uniform the ore the smaller may be the samples; where the ore is spotty, the samples should be large, as is also the case where the ore is loose and breaks irregularly, or is alternately hard and soft.
In cutting a sample the rich spots should be avoided if they are few in number; if there are many rich spots, the groove should include everything along its line. It is a very difficult matter to sample correctly a spotty ore. In the case of a low grade gold ore that consists of quartz carrying free gold, the average cannot well be determined by sampling; a majority of the samples of such an ore will be very low, or blanks, and a few will be very high; the average obtained will be more a matter of luck than a basis for an accurate estimate.