"Merced is, strictly speaking, an agricultural county. Most of its 1,276,800 acres of land is under cultivation and the question of water has long been settled by the introduction of a system of irrigating ditches which is augmented by numerous flowing wells.
"There is very little mineral in the county and only one gold mining company operating (circa 1914). The mineral indications are found in the Coast Range mountains in the southwestern part of the county adjoining Santa Clara County and in the northeastern part adjoining Mariposa County."
"A slate deposit was discovered in 1912 about 11 miles east of Planada, probably the Mariposa slate and of Jurassic age.* It is reported as 1,500 feet in width at the surface, 3 miles in length, and 300 feet in vertical thickness. The California Slate Co., of Planada, has commenced to develop the property. A specimen of the slate examined by the writer yields these results.
(* Page 70 footnote 1: See Turner, H. W., and Ransome, F. L., United States Geological Survey Geol. Atlas, Sonora folio (No. 41), p. 2, 1897.)
"This slate is of dark bluish-gray color, with a somewhat lustrous, very finely granular surface with minute striations along the grain. Its fissility is good. It is very sonorous, indicating a high degree of metamorphism, does not effervesce with cold dilute hydrochloric acid nor show any carbonate in thin section, indicating durability of color. It is graphitic and contains many bronze-colored magnetic particles. Magnetite is not certainly present.
"Under the microscope it shows a matrix of muscovite (sericite) very even in the grain direction with brilliant aggregate polarization, also conspicuous lenses with a nucleus of black mica (biotite). The biotite scales lie mostly parallel to the grain direction and the lenses, partly biotite and partly quartz, are elongated in the grain direction, but the biotite nucleus is crossed by parallel bands of dark inclusions that lie in the cleavage direction. It also contains many bronze-colored metallic particles and minute lenses of a highly magnetic mineral, presumably pyrrhotite (magnetic pyrites). The chief constituents of this slate, named in descending order of abundance, appear to be muscovite, quartz, biotite, kaolin, graphite, and pyrrhotite. Magnetite and rutile are not certainly present.
"This is a mica slate of sedimentary origin, free from carbonate, with good cleavage. It should discolor but little if at all, but its content of magnetic particles makes it unsuitable for electrical uses."
Area: 1,995 square miles.
Population: 24,579 (1920 census).
Location: About the geographical center of the state.
"Merced County as a whole lies in the San Joaquin Valley, and it figures as one of the lesser mineral-producing counties of the state. The 1919 mineral output was valued at $40,350. The decrease from the value of $74,849 in 1918 was due to gold. Gold, platinum, and silver, obtained by dredging, for several years were among the important items. Undeveloped deposits of antimony, magnesite, quicksilver, and limestone have been noted in this county in addition to the foregoing.
"In forty-eighth place, commercial production during 1919 was as follows:
(Headings for the information below are: Substance, Amount, and Value.)
Stone, miscellaneous; ---, $40,350
(* Please note this list does not include sand or gravel quarries.)
The previous version of this web site indicated there was a stone quarry in the area. The current version does not.
"Dickenson Quarry, in T. 9 S., R. 16 E.; S. W. Dickenson, owner. A small quarry of a medium-grained, gray sandstone, which has been developed only in a small way."