1868. | Gold in California. 321 
fied, now presents the appearance of a combination of alabaster and 
black marble, each portion distinctly retaining the structure of the 
original wood. 
The assay of specimens of the cementing pyrites shows that it 
invariably contains small, but very variable quantities of gold. In 
order to ascertain whether this exists in the form of water-worn 
grains, mechanically enclosed within the crystals of sulphide, or in 
the shape of crystals or spongy and filamentary particles, similar to 
those met with in the pyrites of auriferous veins, numerous fragments 
were attacked by nitric acid, and the residue subsequently subjected 
to microscopical examination. 
In this way granules of the precious metal were detected which 
had evidently been worn by the action of running water, whilst others 
appeared not to have been subjected to such attrition. With regard 
to similar deposits in Australia, Mr. Ulrich* remarks, “In the gold- 
drifts (Ballarat, Daylesford, Clunes leads, Loddon River, alluvium 
near Vaughan, &c.) pyrites is often found encrusting or entirely 
replacing roots and driftwood ; such specimens very quickly decom- 
pose on exposure to the atmosphere, and samples have, on assay by 
Messrs. Daintree, Latta, and Newbery, likewise yielded from a few 
pennyweights to several ounces of gold per ton. According to Mr. 
H. A. Thompson, a beautiful specimen of crystallized iron pyrites 
deposited on a piece of wood taken from the drift immediately below 
the basalt, at Ballarat, gave, by assay, 40 ounces of gold per ton, 
and in another case, where only the pyrites from the centre of an 
old tree-trunk was examined, the yield was over 30 dwts. of gold 
per ton. Some of the fine dust obtained by washing out the gold 
at the Royal Saxon claim, Ballarat, yielded, by assay, over 15 oz. 
of gold per ton. When placed under the microscope, this dust was 
seen to be composed of minute crystals of pyrites aggregated into 
round pellets, from 1-300th to 1-100th of an inch in diameter, the 
surface being roughened by the projecting angles of the crystals and 
un-water-worn.” 
The amount of skill and capital necessary for the successful 
prosecution of gold washing or placer mining is usually less than 
is requisite for carrying on quartz mining on a remunerative scale. 
Water is the great agent, by the aid of which placer mining is 
carried on; with a large supply the operations of the miner can be 
cheaply and rapidly conducted, but without it, or with only a 
limited supply, a claim that would otherwise have been highly 
remunerative, may either become valueless, or be only capable of 
affording very irregular returns. 
Placer mines are of two distinct kinds, shallow and deep ; shallow 
or surface diggings are generally found in the beds of ravines or 
* “Notes on the Physical Geography, Geology, and Mineralogy of Victoria.’ 
By Alfred R. C. Selwyn and George H. T. Ulrich, p. 56. Melbourne: 1866. 
