J. Blake—Roscoelite, a Vanadium Mica. 31 
Art. [V.—On Roscoelite, a Vanadium Mie; by JAMES BLAKE, 
M.D., San Francisco, California. 
been principally deposited in fissures in the porphyry, and is 
usually found in layers from a tenth to half an inch thick, and 
seldom extending continuously for more than two or three 
h 
having been washed out from a single panfull; and while at 
the mine I saw $40 taken from a few handsfull. The gold is 
commonly found in the form of fine scales which have been 
deposited between the crystals of the mica. So generally is it 
diffused that it is impossible to find a piece of the mica as large 
as a bean that does not contain gold. The mine is worked b 
compound. When I first discovered the mineral, I expected to 
find a mica rich in chromium, and, on heating some of it ina 
test tube with HCl, I obtained a green solution. Finding that 
by continued boiling with acid the whole of the color was en- 
