From Introduction: "The present report is based on 10 weeks of field work from mid-November 1940 until late January 1941, and 4 days in May 1941. An area of 5 1/2 square miles in and about Del Puerto Canyon was mapped on a scale of 600 feet to 1 inch, and two small areas in the vicinity of the Adobe Canyon and Black Bart chromite mines were mapped on a scale of 200 feet to 1 inch."

From abstract: The Coso quicksilver district, which is in the Coso Range, Inyo County, Calif., produced 231 flasks of quicksilver between 1935 and 1939. The quicksilver mineral, cinnabar, was not recognized in the district until 1929, although the hot springs near the deposits have been known since about 1875...The granitic rock on which much of the sinter rests is considerably altered. The cinnabar was deposited as films and grains in open spaces in the sinter, during one stage in a sequence of hot spring activities that still continues. The amount of sinter in the district is estimated to be about 1,800,000 tons. Although the greater part of this does not contain much cinnabar, the total quantity of such material is large enough to be of interest as a low-grade ore.

Abstract: The manganese deposits of the Paymaster district, in Imperial County, Calif., extend along steeply inclined normal fault fissures which cut Tertiary (?) volcanic breccia and fanglomerate. The ore deposits are in part open-space fillings composed largely of psilomelane, and in part fault breccia replaced by psilomelane, pyrolusite, and manganite. Calcite and rock fragments are the chief impurities. High-grade ore now exposed averages about 40 percent manganese, and contains much barium. About 3,000 tons of ore averaging 42 percent manganese was produced from the district by hand-sorting in 1917-18. It is estimated that nearly the same amount could be produced again, largely from present workings. In addition, a few tens of thousands of tons of milling ore, estimated to contain between 10 and 30 percent of manganese, are believed to exist in veins one to three feet wide within one or two hundred feet of the surface.

This report discusses geologic work conducted in the Strayton district, California on the deposits of quicksilver and antimony.

From abstract: The Parkfield district, one of the minor California quicksilver districts, lies on the southern end of the Diablo Range, in the southeastern part of Monterey County and the westernmost tip of Kings County. (...) Two geologically similar areas, separated by 10 miles of unmineralized rocks, have been mapped. These areas contain (1) sedimentary, volcanic, and metamorphic rocks belonging to the Franciscan formation, of probable Jurassic age, (2) sedimentary rocks of Cretaceous age, (3) a few outcrops of fossiliferous strata assigned to the Temblor formation, of middle Miocene age, (4) large masses of serpentine emplaced along fault zones in post-Miocene time, (5) lenses of silica-carbonate rock formed by the alteration of the serpentine, and (6) large areas of landslide.

Abstract: This report summarizes the results of reconnaissance study of quicksilver deposits in the northwestern corner of Nevada, the northeastern corner of California, and Lake County, Oreg. made in August 1940. The Lene Pine district, Nevada, the Silvertown and Red Hawk properties in California, and the Currier and Glass Butte properties in Oregon were included. The first two of these require further development before a definite opinion as to their value can be formed. The Red Hawk mine has yielded high-grade ore, but the ore bodies so far worked are very small and scattered. The small amount of development at the recently opened Currier mine has yielded encouraging results. The deposits in the Glass Buttes are large but of such low grade that thorough sampling would be needed to determine their value. In general the region appears to warrant more attention from quicksilver prospectors than it has yet received.

From abstract: Scheelite ore bodies occur at widely separated localities in the Sierra Nevada near Bishop, Calif. The scheelite is found in altered sedimentary rocks at or near the contact between granitic rocks and limestones that are partly changed to silicate rocks composed largely of garnet. Mineralization was closely connected with the intrusion of the granite, the latest of the varied intrusives that make up the rocks of the Sierra Nevada.