at Sulphur Bank, California. 29 



coming water is abundant, there is only hot mud between the 

 fragments, but in other places where the rock is drier and the 

 solfataric action finished, the fragments are firmly cemented 

 with a paste of consolidated mud containing disseminated 

 metallic sulphides, or often wholly with deposits from the sol- 

 fataric waters ; and thus the vein becomes a mere breccia 

 united by a paste of cinnabar, pyrites and silica, put mostly 

 cinnabar. The spaces between the fragments are sometimes 

 entirely filled with deposit, sometimes only partially filled, 

 leaving hollow spaces between. In this case the mass may 

 have the appearance of an aggregation of round pellets of 

 cinnabar, but on breaking these pellets they are found to have 

 an angular fragment of rock as a nucleus. The deposits lining 

 or filling the cavities are most commonly cinnabar, but some- 

 times pyrites, or silica, or all of these in alternate layers. The 

 silica was found in all stages of consolidation, — sometimes chal- 

 cedonic, sometimes cheesy, and sometimes gelatinous.* The 

 accompanying figure, roughly drawn from a specimen in our 

 possession, will give a general idea of the appearance of the 

 richer portions of the ore-body. 



ty 



The vein (if such it mav be called) is largely in the brec- 

 ciated stratum already described, but is apparently not wholly 

 confined to it. It is extremely irregular, sometimes widening 

 out to many yards, then thinning down to a few inches or 

 even pinching out and disappearing entirely, to reappear again 



- • i ' ' '• - i t • r..t, „,.,.,. - . v. _• ' i 



