Mineralogy and Geology. 137 
by that mineral, although of two pieces of wood lying in close 
proximity to ea ch other, one may have become silicified, whilst the 
other is asses by iron pyrites. 
of several specimens of the cementing tebe showed * 
that it savacidity contained a certain but very variable amount 
gold. In make to ease whether this exists in nen iP eee of 
weights be several ounces of gold per ton. 
rings.—Hot and Spear _— are exceedingly nume- 
rous oi California; and considerable accumulations of 
sulp ur, together with sibel of etait solfatara action, are 
€ most remarkable instance on the Pacific coast of the actual 
growth, on a large scale, and at the present time, of mineral veins, 
mg probably that afforded er the boiling springs in Steamboat Val- 
ley, about seven miles northwest of the great Comstock silver 
Vein in si State of Nev wid: 
cones first group of crevices ‘compris ises five iene 
eprings ex ending ina straight line, and parallel to each other, 
for a tintane of above 3000 feet. These fissures are partially 
filled by a siliceous incrustation, which is being inn pong HP deposi 
on ‘the sides, whilst a longitudinal central crevice allows of 
the ings of boiling water or steam. On the most foerans of 
tu 
: a gat to ten feet. These waters are alkaline, aad 
fontain, in addition to carbonate of soda, the sulphate of that base, 
oxydof iran The sili eel 
bands parallel with ai Scien op the fissures ; and spongy de- 
Posits accumulate around some of the points of most most active emer 
gence, 
At a considerable distance to the west of those above described, 
a fissure having the same origin is observed; but this is no longer 
