472 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



Tlie usual mineral association consists of cinnabar and traces of native 

 mercury, with pyrite and marcaslte, silica and carbonates ; but sulphur 

 occurs at three mines, chalcopvrite is not very uncommon, stibnite is found 

 (though rarely), gold or auriferous pyrite occurs in a few cases, niillerite in a 

 number of instances, and barite in one. These substances and their decom- 

 position-products ai-e rare. Excepting in Steamboat Springs, at Calistoga, 

 and in the Barcelona mine, I do not know of silver, lead, or zinc minerals 

 accompanying cinnabar in the western United States. A new bitumen, two 

 new chromium minerals, and a red antimony sulphide have been detected 

 with cinnabar in this investigation. 



The great similarity of the deposits points to a connnon history for 

 them all. The evidence is strong in many cases that they have been 

 deposited from hot sulphur springs and the remainder have probably been 

 produced in the same wa}*. The inclosing rocks have been without effect 

 upon the deposits, for neai-ly all the I'ocks in the Coast Ranges inclose ore 

 bodies. These facts point to a common, deep-seated origin. 



It has often been asserted that quicksilver ores do not form deposits 

 similar to those of the ores of other metals, but I can find no evidence of 

 this Stockworks, impregnations, and regular veins all occur, and no other 

 or peculiar form of deposit is known to me. Many of the discussions as to 

 whether or not deposits are veins depend on the various uses of this word. 

 To miners it usually means deposits along, or directly connected with, a 

 distinct fissure ; to a geologist a vein means a deposit between well defined, 

 nearly parallel walls which have once been in contact. Irregular bodies of 

 ore, even those connected with distinct fissures, are known to him as stocks, 

 stockworks, or by some similar name. I propose to call the contents of dis- 

 tinct fissures with very irregular walls cliamlered veins and the irregular 

 openings or ore bodies connected with a main fissure vein cliamhers. A 

 chambered vein may then be defined as a deposit consisting of an ore- 

 bearing fissui'e and ot ore bodies contiguous with the fissure, but extending 

 into the country rock. The greater part of the cinnabar deposits would 

 come under this definition, which woiild also apply to many deposits of 

 other ores. If this term were adopted, simple fissure vein would still 

 describe the form of deposits now known to mining geologists as veins. 



