Report of the State Mineralogist, Issue 17

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State Office, 1921 - Gold mines and mining

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Page 231 - Portland cement is the product obtained by finely pulverizing clinker produced by calcining to incipient fusion an intimate and properly proportioned mixture of argillaceous and calcareous materials, with no additions subsequent to calcination excepting water and calcined or uncalcined gypsum.
Page 25 - The country rock is jasper, thin layered and separated by seams of shale. The jasper layers differ in thickness from a fraction of an inch to several feet. The same layer varies in thickness, pinching out locally In many places. Most of the shale seams are thin. Both shale and jasper are greenish gray except where stained red or black by iron or manganese. The dip of the layers is about 35 W., the strike being a little east of north.
Page 10 - The important uses of quicksilver are the recovery of gold and silver by amalgamation, and in the manufacture of fulminate for explosive caps, of drugs, of electric appliances, and of scientific apparatus. By far the greatest consumption is in the manufacture of fulminate and drugs.
Page 12 - Washington magnesite resembles dolomite and some crystalline limestones in physical appearance. Its color varies through light to dark gray, and pink. In California the known deposits are mostly in the metamorphic rocks of the Coast Ranges and Sierra Nevada Mountains, being associated with serpentine areas.
Page 207 - ... detail by various writers, especially by Becker (4) and by Forstner (1) p. 169, the latter of whom says : 'The three ridges In which the deposits occur are to a great extent formed by serpentine, especially the two first named. The serpentine is associated with metamorphlc sandstone and jaspllltes. Large bodies of croppings can be found in each of these ridges, having also a general northwestern trend, but not coinciding with the backbone of the ridges. 'In the New Almaden ridge the most extensive...
Page 207 - ... that the fissures wherein the orebodies have formed have invariably a serpentine footwall; hence the serpentine must be considered to occur underground In a continuous body through this entire territory and to be in places covered by overlying sandstones and shales. Southwest of Capitancillos Creek lies another parallel exposure of serpentine, contiguous to which the outcrops of the Costello mines are found. The Santa Teresa and Bernal mines are located In the serpentine of the Santa Teresa hills,...
Page 206 - ... the New Almaden and the New Idria mines. The New Almaden, oldest of the many prospects now known in the Coast Ranges, is the oldest from which production has c,ome. The New Idria, located farther south, though some 80 miles distant, has a similar geologic setting. New Almaden, WW Bradley (5) p.
Page 308 - Creek. — Gypsum deposits of varying quality occur for many miles along the lower foothills of the Sierra Nevada, reaching from Caliente on the south nearly to Porterville on the north. In the valley of Cottonwood Creek, 5 miles north of Pampa station, on the Southern Pacific Railroad, the beds are rather extensive, and a number of mines have been opened. The gypsum here seems to occur both as a crust upon the surface and as interstratified beds. The latter vary in thickness from 20 inches to 5...
Page 207 - At the surface the serpentine shows in large detached bodies surrounded by the sandstones and shales of the Franciscan series and having a general northwestern trend. This general direction of the serpentine exposures is important in connection with its occurrence underground, proven in the New Almaden mine. The line of ore croppings runs from Mine Hill to the American shaft, passing about 600 feet southwest of the Randol shaft. The underground workings in this territory have shown that the fissures...
Page 25 - ... shale seams are thin. Both shale and jasper are greenish gray except where stained red or black by iron or manganese. The dip of the layers is about 35 W., the strike being a little east of north. The ore occurs in several interbedded lenses or pockets a few feet thick and of small extent. It is a soft, friable black oxide contained in cavities between numerous intersecting quartz seams, or as seams intersecting jasper fragments. Most of the quartz seams are later infiltrations, but the fragments...

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