S. B. Christy— Genesis 6f Cinnabar Deposits. 455 
in most cases, although some ore has been found above it. It 
varies in thickness from one to two feet. In anal zing this 
there was found a very small residue insoluble in th 
chloric acid, which under the microscope proved to contain 
fragments of iron pyrites. ee substance had been pow- 
In the various workings there occurs sandstone, particularly 
in the Cora Blanca. The sandstones seem always to overlie the 
vein matter,” though in the latter mine they are sometimes 
Bees with cinnabar, and are said to wee contained when 
cance of these latter rocks I have not as yet been able to deter- 
mine. It is altogether probable, however, that they are more 
or less local in their origin, being the result of slightly varying 
conditions which panes during their deposition. Such a 
supposition would account for the gradual change of the 
sandstones into slates, Ghd often takes place in such a man- 
ner as to it difficult to determine to which class to 
assign them. 
Native mercury occurs rarely; chiefly in the sandstones of 
the Cora Blanca, but also in the 1,500 and 1,600 feet levels 
of the Randol shaft, where it ran out of the ‘shattered Alta 
upon opening out the vein-matter at places where it was much 
broken up by faultin 
In many cases Bt micro: crystals of cinnabar are most inti- 
hos 
mately mixed with t of dolomite, and occasionally with 
those of quartz. 7 Sanatee Atha when apparently pure to 
the eye, is so thoroughly impregnated with bitumen that a 
lump of it when distilled out Pt contact with the air leaves a 
carbonaceous resi 
Throughout this interesting mine oe are many evidences 
both of chemical and of mechanica 
A strongly alkaline spring with free acon acid (the New 
Almaden Vichy spring) is still active at the Hacienda. Occa- 
sional] mph ig sulphydric as well as carbonic acid are 
peed by the d In the mine ‘“slickenslides,” or ps bard 
polished as —. as glass by slipping on each other, are fre- 
quently met with; and often large masses of se Pees ntine are 
Lag off bodily and are buried in the superincumbent mass 
f Alta. 
Y Fhe ore is very irregularly distributed throughout the vein- 
matter, » regen ey disappears oe and reappears in one 
