GOLD. 1li 
Obs. Native gold is mostly confined to quartz, intersect- 
ing in veins, or interlaminated with, suberystalline slaty or 
schistose rocks, especially hydromica and chloritic slates. It 
occurs sparingly in similar or other veins in granite, gneiss, 
or mica slate. It has also been found in traces, according 
to J. J. Stevenson, in the trachytes of Colorado, and in 
Silurian and Carboniferous quartzytes.. 
The quartz intersects the slaty rocks in veins and lies in 
thick seams between their layers. It is frequently cellular 
for a considerable distance from the surface owing to the 
alteration and removal! of pyrite, galena, or other “mnetallic 
ores that may be accompaniments of the gold, and the 
cavities are usually rusty with oxide of iron, and sometimes 
contain particles of sulphur left by the decomposing pyrite, 
and also strings or lamine of gold. The rock in this cav- 
ernous state is rather easily quarried out; but deep below, 
where the minerals are not removed by decomposition, mining 
is far more difficult. 
Pyrite itself is nearly as hard as quartz, when unaltered, 
and readily strikes fire with a steel. This pyrite is often 
very abundant, and contains throughout it considerable 
gold; but the gold is so finely distributed, that little of it 
can be removed by the ordinary process of crushing and 
amalgamation; nature’s way consists in decomposing the 
pyrite and thereby making it drop its load. The galenite 
of a gold region is also usually auriferous. 
Gold sometimes occurs in the slate rocks adjoining the 
veins, though mostly confined to the latter. Auriferous 
quartz often contains no gold visible to the naked eye. 
But while quartz veins are to a large extent the actual 
repositories of the gold in its native state, a very large 
_ part of the gold derived from auriferous regions has come 
from the sand and gravel beds, in which it occurs in flat- 
tened grains, and sometimes in lumps and nuggets. By dif- 
ferent methods—erosion by running waters, ‘movements of 
glaciers, natural decomposition, and other disintegrating 
action—the gold-bearing rocks have been extensively re- 
duced to earth and stones, and this loose material has been 
distributed along the river courses, making vast alluvial or 
diluvial oravelly formations. From these “gravels the gold 
is obtained by simple washing, thus taking adv antage of the 
high specific gravity of gold. Streams are carried in aque- 
ducts and thrown in great jets against the gravel blufis to 
