104 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



No. f)8, Sulphur Bank, is a greenish-gray, schistose rock, consisting 

 chiefly of glancophane and zoisite. The hxtter occurs in imperfect prismatic 

 crystals, with a maximum length of from 0.1""" to 0.2'""". The prisms show 

 longitudinal furrows. The zoisite is distinctly dichroitic anrl has a faint 

 olive-green tint when the prisms are parallel to the princij^jal section of the 

 nicols. Sections perpendicular to the main axis are square, often with one 

 truncated corner. The extinctions are normal and the colors of interference 

 are gray to yellow in the prisms, but more x'nld in granvilar aggregates. 

 The angle of the optical axes appears to be lai-ge. 



Glaucophane, in needles and long, impe'.-fect, neaidy parallel prisms, 

 gives the rock its cleavage. Quartz, albite, muscovite, and titanite arc 

 present. 



The rock was reduced to a grain of one-third of a millimeter, and sep- 

 arated bv the Thoulet method Avith the followin<r result: 



A complete analysis of the rock gave the following result: 



Lo.<;s at 100*^, n-0 0.000 



Loss above ino^, H-O : 3.842 



Silica, SiO- 41). 680 



Phosphoric acid, P-O-' 0.206 



Tit.iiiic aiicl, TiO- 1.305 



Aliimi iia, Al-0^ 13. 603 



Ferric oxide, Fc-C 1.863 



Ferrous oxide, 1\0 8.606 



Maiigaiious oxide, MnO 0.038 



Liiiio, CaO 10.CC7 



Majjnesia, JI-jO '. li. 265 



Sod.a, Ka-O 3.091 



Potassa, K-0 0.119 



Total 03.584 



