OLD MINES
OF
SOUTHERN CALIFORNIA
Desert-Mountain-Coastal Areas
Including the
Calico-Salton Sea Colorado River Districts
and
Southern Counties
1965
Frontier Book Company
Toyahvale, Texas 79786
Reprinted From
The Report of The State Mineralogist
1893
Limited to 1000 copies
LOS ANGELES COUNTY.
By W. H. Storms, Assistant in the Field.
The mining industry in this county is not as extensive as that ofsome of the neighboring counties, but there are mines in Los AngelesCounty of unquestioned value, and others which have a prospectivevalue, dependent to a great extent upon the success achieved in workingcertain base ores, which occur in comparative abundance.
THE KELSEY MINE.
One of the most interesting mines in the county is located in therugged mountains about 8 miles from the town of Azusa, in the SanGabriel Cañon. It is commonly known as the Kelsey Mine, and hasbecome famous as a producer of silver ore of fabulous richness.
The country is made up almost entirely of metamorphic rocks, havingschistose, gneissoid, and massive structure. Both hornblende andmica occur in these rocks abundantly, the former being frequentlyaltered to chlorite, or by further change to epidote. Dikes of porphyriticrock have been intruded into the crystalline schists. In the immediatevicinity of the Kelsey vein are intrusions of a dark green, muchdecomposed, and shattered rock, probably diorite. Faults, great andsmall, are numerous throughout the region. Within a few hundredfeet of the mine is a great fault, which may be plainly seen cutting themountain. The displacement must reach many hundreds of feet. Ithas resulted in bringing in contact on a horizontal plane rocks ofentirely different character. On the south side of the fault the rocksare made up of quite regularly bedded micaceous sandstones, more orless schistose, and having a prevailing buff or light gray color. Theserocks dip east at an angle of 20° to 30°. On the north side of the faultthe rocks are harder, of a dark gray color, and containing considerablehornblende. These rocks are more gneissoid and massive than schistose.The dip is much less regular than on the south side of the displacement.Large, lenticular masses of quartzose and feldspathic rockare of frequent occurrence in the hornblende gneiss, evidently the resultof the segregation of the contained minerals. On the whole there ismuch more evidence of the disturbance on the north side of the faultthan on the south side. It is in this area of greatly disturbed stratathat the Kelsey vein has formed.
The vein is of the fissure type and occupies the line of a fault plane,that at first, perhaps, was a mere crack, but which has become enlargedby the movement upon themselves of the rock masses forming the walls,resulting in a grinding and crushing of the rocks by the attrition andpressure incident to this movement. Into this crevice mineral watersfound their way, carrying in solution the minerals now constituting thevein.
FAULTING AND TORSION
OF THE
KELSEY VEIN
The Ore.—Th