866 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



deposits to the south, and they show that the series of chemical phenomena 

 leading to the deposition of cinnabar have been repeated at long geograph- 

 ical intervals. At the north, as to the south also, the deposits are formed at 

 no great distance from lavas. The entire belt of country from the mines of 

 Douglas County, Oregon, to Santa Barbara is thus structurally continuous 

 and is marked by irregularly distributed volcanic phenomena and cinnabar 

 deposits. In a broad sense the entire zone, six hundred miles in length, 

 may be considered as a quicksilver belt. It will be convenient to take up 

 the deposits not described in the foregoing chapters in the order of their 

 latitude, beginning at the north. 



North of Clear Lake — The dcposlts of Douglas Couuty, in Oregon, are sit- 

 uated on the western flank of the Cascade Range, the base of which is 

 composed of granite and metamorphosed sandstones precisely similar to 

 those at Knoxville. and other points to the south which have been minutely 

 described in Chapter III. The crest of the range is occupied by lavas. 

 The New Idrian mine is said to be the principal deposit. It was visited in 

 1880 by Mr. H. W. Leavens and it is reported by him to be a vein in sand- 

 stone. The ore is cinnabar accompanied by iron oxides and, according to 

 the report, by manganese oxide.^ In 1882 fifty flasks of quicksilver ai-e 

 known to have been produced by the mines of this region. 



Near the boundary between California and Oregon, in Del Norte 

 County, Rockland district, in the neighborliood of the Diamond copper 

 mine, cinnabar and native quicksilver were described as occurring in a 

 whitish-gray rock in 18J4.^ I know of no second notice of this occur- 

 rence. 



The quicksilver district of Trinity County, California, is in its north- 

 eastern corner. The rocks are mainly metamorphosed sediments, largely 

 serpentinized, but volcanic rocks are said to occur at intervals, and there 

 are mineral spi'ings directly at the principal mine, the Altoona (formerly 

 called the Trinity). The rocks immediately associated with cinnabar are 

 serpentine and sandstone. The ore occurs in part as a tabular impregna- 



' statistics and Technology of the Precious Metals, liy S. F. Emmous and G. F. Becker, pp. 27 

 and 28. 



'Milling and Scientific Press, vol. 29, August 15, 1874. 



