It is very important to take good and representative samples from the gold deposit. The gold prospector must following and intelligent and reasonable procedure. Basically, it is necessary use a light pick or a chisel and hammer to detach small portions of the rock, cutting a rough groove across the vein. Sometimes the tunnel occupies the whole width of the vein in which case the prospector has to make a circular groove clear around the tunnel, across floor, roof and walls. The fragments from this work drop into a plastic bag.
Basically, according to the length of the vein or the need for great accuracy, the prospector may repeat the sampling operation at intervals which may be every 1 m, 3 m or 6 m. at intervals of 6 meters, the samples may be mixed and with a divide the result into four parts, throw away two and retain two. Once the sample is bagged, it is necessary to write the location of the sample. When the material is friable, the sample would be more representative due to the high proportion of fine material. In some occasions, as a check upon this work and for reference in case of any accident to or any tampering with his samples in transit, a prospector must take a grab sample from his broken rock before quartering it. In this way, he may take a chunk of some peculiar rock such a porphyry or some peculiar streak in the gangue.
It is sometime important in a vein to find out what rock or portion of rock carries the most value. For instance, a vein carries gold clear across its entire width. Now, this vein proved to be a decomposed dyke or porphyry impregnated with pyrite and gold and through the dyke ran a net work of little narrow quartz veins or veinlets. During sampling, it is important to keep those fragments that came from quartz veinlets apart from those which came from porphyry gangue. The result could be a porphyry, constituting of course the main element, to the remaining part and the gold concentrated in quartz veinlets.
It has been noted that in a vein there will be parts richer than others, pay streaks as they called, which it is important to distinguish, also certain metallic minerals in the vein carrying greater values than others. In this way, if pyrites are decomposed, may prove too poor to treat gold or in a silver deposit, streaks of gray copper may be very rich. In a gold deposit, it is important for the prospector to find out to what depth surface decomposition or oxidation has penetrated, because in this brown rusty matter will likely be most of the free gold. Whilst when the unoxidized pyrite makes its appearance the ore is no longer free ore. Sometimes, however, though the oxidized brown gossan may play out and succeed to white quartz, the latter, if it be not too hard, white quartz may carry some free gold.
Yellow lines indicate the sampling area