The quicksilver resources of California . I LAKE COUNTY, 63 and the latter determination is generally accepted. Thesebasalt bowlders may be a flow from the craters, yet discernibleto the northeast of the bank, or may have been ejected from avent close to the bank, which has as yet not been to the present time this basaltic flow has been found every-where overlying the altered sedimentaries. As the cinnabardeposits are not restricted to the territory covered by the lavaflow at the Bank [see Fig. 14], and as most careful investiga-tion has failed to disclose any cinnabar or mercury
The quicksilver resources of California . I LAKE COUNTY, 63 and the latter determination is generally accepted. Thesebasalt bowlders may be a flow from the craters, yet discernibleto the northeast of the bank, or may have been ejected from avent close to the bank, which has as yet not been to the present time this basaltic flow has been found every-where overlying the altered sedimentaries. As the cinnabardeposits are not restricted to the territory covered by the lavaflow at the Bank [see Fig. 14], and as most careful investiga-tion has failed to disclose any cinnabar or mercury in theundecomposed basalt, this basalt can not be the source ofthe metal. The upper crust of the lava deposit, to a thickness of a fewfeet, consists of a white silica, the residue of the complete de-composition of the basalt, by the combined action of the highly -?a 3<i I fSouldt arreL 3ac/^/< cCJ3^S« //i Fig. 15. Sulphur Bank Mine—Elevation of Upper Wagon Spring Cut at (X). sulphurous solfataric waters and the atmosphere, forming sul-phuric acid ( + 40 = *), which decomposed all thesilicates in the rock and left the pure silica. Immediatelybelow the surface zone, where oxygen was not so abundantlypresent, free sulphur was formed (H:;S -f O ^ -f S). Thistook place to such an extent that originally the property wasworked for sulphur. About 2000 tons of sulphur have beenextracted. The basalt occurs in places as masses of bowlders, whichnear the surface are surrounded by shells of decomposedmaterial of grayish color and very much disintegrated. Belowthese bowlders and in places reaching very near the surface,as in the bank of the Upper Wagon Spring cut [see Fig. 14 atX and Fig. 15] and in the Apex cut, the basalt has a more orless bedded form. When first uncovered, the basalt bowldershave a rough surface; but when in contact with the atmos-phere for a
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