ASSOCIATED MINKKALS IN THE VPHNS. 231 



of the quartz. Sulphides are most coininon, but compounds of arsenic, 

 antimony and tellurium also occur. A list of the associated minerals in 

 the quartz-veins would include the following species : 



Iron-pyrites (universsally present). Tetrahedrite. 



Pyrrhotite (not common). Antimonal lead ^^ulphicles (rare). 



Copper- pyrites (common). Cinnabar (rare). 



Zinkhlende (common). Tellurium minerals — Ilessite, Altaite, 



Galena (common). Calaverite, Sylvanite, Petzite, ^lelun- 



Molyl)(lenite. ite (freiiuent, in small quantities). 



Arsenical pyrites (common). Nickel and cobalt minerals (very rare).* 



Marcasite is noticeably absent from _o-old deposits as noted by Mr 

 Louis. I have once seen it, however, from a mine at Grass Valley. 



These metallic minerals, usuall}^ referred to as "sulph.urets," contain 

 more or Icv^s gold and silver and are freciuently very rich, the concentrates 

 ranging from thirty to several hundred dollars i)er ton. 



Bismuth and cadmium have been found in small quantities in the 

 concentrates from the Nevada City mines, the former also in Shasta 

 county. t Compounds of tin, wolframium, uranium, boron,! phosphorus 

 and fluorine appear to l)e entirely absent. Cuprite, bornite and chalco- 

 cite are also lacking. Cobalt and nickel minerals are occasionally present. 

 Titanium occurs sparingly. 



A slight influence of the wall-rock upon the character of the mineral 

 association cannot be denied. It appears to be a fact that veins in grano- 

 diorite contain more suli)hurets than those in other rocks. Pyrrhotite 

 appears to be entirely confined to veins in this rock. It is known only 

 from the vicinity of Washington, in Nevada county, Sonora, in Tuolumne 

 county, and Westpoint, in Calaveras county. Veins in black sedimentary 

 slate or on the contact between greenstone and slate seldom contain 

 much besides iron-])yrites, and perhaps arsenical pyrites ; neither are 

 veins in augite-porphyrite or diabase usually rich in sulphurets. V^eins 

 in gabbro often contain copper. These are no strict rules, however, and 

 the influence of the wall-rock may, on tlie whole, be considered as re- 

 markably small. 



Distribution ok tiik Cold in tiik Vkins. 



Gold is univi-rsally distribut'jd in tlic (juartz-veins of California. The 

 definition of what is ore, or (juartz j)aying for ('X[)loitation and mctallurgic 

 treatment, will necessarily vary at <liflerent times and in different i)laces. 



•Compare a paper by Henry Louis In Min. Magazine, vol. x, 1893, p. '241, on the minerals asso- 

 ciated with gold deposits in genprul. 



t R. IVarce, in Trann. .\m. Inst. Min. Eng.. vol. xviii, |». H7. 



t Tourmaline has been tound in the abnormal veins of Mea<low I^ako, Nfvadii county. Am. 

 Jour. Sci., vol. xlvi, l8y.'J, article 30. 



