S o THE PROSPECTOR'S HANDBOOK. 



GOLD. 



To detect free or native gold in a piece of specimen 

 rock, in sand or gravel, the sample should be carefully 

 examined by means of a magnifying glass, if the eye is 

 insufficient. The particles of gold, if present in the free 

 state, will probably be distinct, whether wet or dry, and can 

 easily be distinguished by an expert from discoloured mica, 

 iron, or copper pyrites. The usual colour of the metal is 

 well known : but it must be borne in mind that in some 

 localities, such as in New South Wales, Australia, and Costa 

 Rica, it is often found of a very light colour ; indeed, some- 

 times it looks like not very yellow iron pyrites. Gold pre- 

 sents the same colour from whatever direction it is looked 

 at. To the prospector this is a guiding test. If a gold 

 grain be detached from a rock, or selected from sand or 

 gravel, it can be flattened out by hammering and can be 

 cut in slices, whereas those substances likely to be mistaken 

 for gold are reduced to powder when pounded. Iron pyrites 

 is too hard to be cut by a knife, while copper pyrites affords 

 a greenish powder. Besides, pyrites ore, when heated, 

 gives off a sulphury odour. Mica, which when discoloured 

 may be frequently mistaken for gold, is not sectile, and has 

 a colourless streak ; it can thus be distinguished from the 

 precious metal. It may be well, too, to know that a speck 

 of gold is not altered in colour or appearance by hydro- 

 chloric acid. As the quantity of gold in rock is usually 

 very small and to be payable it need not be otherwise 

 the most and only accurate way of determining its quantity 

 is by means of scorification or fusion in a crucible, and 

 afterwards by the cupellation process. This, however, is 

 not always practicable in an out-of-the-way place, and, con- 

 sequently, more simple means are generally sought for by 

 prospectors in order to obtain a rough assay ; and as gold 

 is usually, though not always, met with in the pure metallic 

 state, such are to be in a great measure depended upon. 

 At the same time, it must be remembered that frequently 

 the gold occurs as a very fine powder, invisible to the eye 

 or even under a magnifying lens, and also that the grains 

 probably due to sulphur of arsenic may be coated with a 



