—— a 
B. Silliman, Jr., on the New Almaden Quicksilver Mines. 191 
beyond, toward the place called Bull Run, occasional loose 
boulders of drusy quartz, with more or less well characterized 
te and combs; accompanying which is an ochraceous or 
erruginous deposit, such as frequently forms the outcrop of mee 
tallic veins. here is, however, no such thing as a well charac- 
terized vein, the quartz and its associated metals occurring rather 
in isolated masses or bunches segregated out of the general mass 
of the metamorphic rocks, and connected with each other, if at 
all, somewhat obscurely by thread veins of the same mineral. 
by means of which all the ore from the various workings of the 
mine is conveniently discharged from the cars, which convey it 
n order to reach the lower workings of the mine, the ob- 
Server may employ the bucket as a means of descent, or he may, 
i & more satisfactory manner, descend by a series of ladders and 
Steps, not in the shaft, but placed in various large and irregular 
penings, dipping for the most part in the direction of the mag- 
netic north, and at an angle of 30° to 85°. These cavities have 
€n produced by the miner in extracting the metal, and are 
f vast ortions; one of them measures 150 feet in 
a wt 0 rop 
length, 70 feet in brealteh; and 40 feet in height—others are of 
Smalle 
er dimensions; and they communicate with each other 
Sometimes by narrow passages, and at others by arched galleries 
Cut through the unproductive serpentine. — : 
Some sitibers of the mine are heavily timbered to sustain the 
Toof from crushing, while in other places arches or columns are 
left.in the rock for the same purpose. _ : 
1 2. Phe rincipal minerals associated with the cinnabar are quartz 
which usually occur together in sheets or 
