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.

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

From abstract: The Blue Wing district, Lemhi County, Idaho, is not only the principal tungsten mining district in the State but it has recently become one of the leading producers of tungsten in the United States. So far only one mine in the district is productive, but other prospects are being actively developed.

Abstract: The presence of cinnabar in the Wild Horse district, in western Lander County, Nev., has been known since about 1916, but little ore was produced until 1940. In that year and early in 1941, deposits discovered in 1939 were mined to apparent exhaustion by the Wild Horse Quicksilver Mining Co., which had produced 827 flasks at the end of April 1941. The district is underlain by moderately deformed sandstone, shale, and limestone of Lower and Middle Triassic age, locally covered by remnants of a mantle of Tertiary fanglomerate, tuff, and lava. The Triassic rocks are partly silicified, and cinnabar has been found in and near silicified rock, particularly the silicified limestone at the base of -the Middle Triassic. The ore bodies so far discovered were individually small and ill-defined, and had an average tenor of less than 0.5 percent of quicksilver. Other similar ore bodies are to be expected at moderate depths, but the cost of exploration for them may, perhaps, prove excessive.

From abstract: Deposits of vanadium-bearing sandstone are widely distributed in western Colorado and eastern Utah and have been the principal domestic source of vanadium, uranium, and radium. Except during a few years when operations were relatively small, deposits at one or more places in this region have been intensively mined since 1909. Production has increased considerably each year since 1937.

From abstract: Tin-bearing veinlets are exposed in a small area near Izenhood Ranch, 22 miles north of Battle Mountain, Nev. They occur in thick rhyolitic flows of Miocene (?) age, and wood tin, found in the gravels of arroyos that head in the surrounding rhyolite, presumably comes from -other veinlets not yet discovered. The exposed veinlets are about 20 feet in maximum length and a quarter of an inch in average thickness. Parallel and reticulating veinlets form lodes 4 to 6 feet thick and 15 or 20 feet long. Virtually no cassiterite is disseminated in the wall rock.

From introduction: Lode and placer deposits of massive topaz rock were discovered near the old Brewer gold mine in northwestern Chesterfield County, S. C., in 1935. Preliminary tests have shown that this rock can be used in the manufacture of refractory ware and as a source of mullite, thus augmenting supplies of kyanite that have been coming from India.

From introduction: In this study the Geological Survey and the Bureau of Mines, United States Department of the Interior, cooperated. The author prepared detailed geologic maps showing the surface topography, geology, and workings of 11 mines, and the underground workings and geology of 7 of these; the Bureau of Mines engineers directed diamond-drilling and.bulldozer-trenching. The locations of the detailed maps are shown on plate 23, an index map overprinted on a segment of the map made by Reed and Wells.

From Introduction: "Scattered throughout the Colorado Front Range, there are many small copper deposits, believed to be of pre-Cambrian age. The have been widely prospected but have produced little or no ore. In one of these, the Copper King mine, near Gold Hill, Colo., nickel was discovered in 1930, and development in the following years has exposed some 25,000 tons of ore containing from 2 to 3 percent of nickel. No other nickel deposit is known in the Front Range, but a somewhat similar deposit has been opened in Gem mine, near Canon City and about 120 miles south of Gold Hill."

This report describes field work and research done in two areas of ultramafic rocks containing chromite deposits are known at the south end of Kenai Peninsula, Alaska. The Red Mountain is the other area covered in this report.

From introduction: The Red Bluff Bay area was examined briefly for the Geological Survey by John C. Reed and others in 1939. During the summer of 1941 the writers, with R. E. L. Rutledge, mapped this area on a scale of 1:12,000, and examined the serpentine masses in the interior during the course of reconnaissance trips into the surrounding region.

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.

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 Introduction: "The Mount Vernon nickel-gold deposit is 4 1/2 miles southeast of the city of Mount Vernon, Skagit County, Wash. The writers believe that the nickel was originally present in the serpentinized peridotite and that it was dissolved and redistributed by ascending hydrothermal gold-bearing solutions while the serpentine was being altered into the silica-carbonate rock."

Abstract: The Three Kids manganese district, in Clark County, Nev., has produced between 15,000 and 20,000 tons of ore, which contained between 30 and 40 percent manganese, 1.5 percent iron, and 12 percent silica. It is estimated that the reserves in the district aggregate about 5,500,000 tons of ore averaging about 10 percent manganese. Of this amount about 800,000 tons contains more than 20 percent manganese and 4,700,000 tons contains from 5 to 20 percent manganese. The manganese ore is a sedimentary deposit and consists of wad interbedded with lake or playa sediments belonging to the Muddy Creek formation of Pliocene (?) age. Where the manganese content is as high as 30 percent, the wad forms thick massive beds separated by thin almost barren partings. Where the content is low, the wad forms very thin lenses or small irregular blebs scattered through sandstone, or a cement for the sand grains. The zone of manganiferous beds ranges from about 10 to 75 feet in aggregate thickness, but at most places the thickness is between 25 and 40 feet.

From abstract: Cassiterite and spodumene, of possible economic importance, occur in a belt, 24.5 miles long and 1.8 miles in maximum width, extending southwestward from Lincolnton to Grover, N. C. This belt is in the Piedmont province, an upland with an average altitude of 1,000 feet, and is readily accessible by rail and highway. The region is underlain by crystalline limestone, quartzite, schists, gneisses, and granite. The rocks strike northeast and, in most of the belt, dip steeply northwest. Most of them are deeply weathered.

From Abstract: "This report describes the occurrence of the mica and its physical properties among which is an unusually wide range of colors. A table is presented showing the results of power-factor measurements made by the National Bureau of Standards on 196 samples of sheet mica from 109 mica mines and 15 feldspar mines.It is concluded that more systematic planning of mica mining, for the district as a whole. would result in an average yearly production of at least 90,000 pounds of relatively clear sheet and possibly much more."

From abstract: Cassiterite was discovered along Irish Creek in the Blue Ridge in the northern part of Rockbridge County, Va., in 1846, but active prospecting and development work were not begun until 1884. The production has been small, probably less than 1,000 tons of ore, and has come chiefly from workings on Panther Run, a small tributary near the headwaters of Irish Creek.

From abstract: The manganese deposits of the Artillery Mountains region lie within an area of about 25 square miles between the Artillery and Rawhide Mountains, on the west side of the Bill Williams River in west-central Arizona. The richest croppings are on the northeast side of this area, among the foothills of the Artillery Mountains. They are 6 to 10 miles from Alamo. The nearest shipping points are Congress, about 50 miles to the east, and Aguila, about 50 miles to the southeast. The principal manganese deposits are part of a sequence of alluvial fan and playa material, probably of early Pliocene age, which were laid down in a fault basin. They are overlain by later Pliocene (?) basalt flows and sediments and by Quaternary basalt and alluvium. The Pliocene (?) rocks are folded into a shallow composite syncline that occupies the valley between the Artillery and Rawhide Mountains, and the folded rocks along either side of the valley, together with the overlying Quaternary basalt, are broken by faults that have produced a group of horsts, grabens, and step-fault blocks.

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.

From abstract: The Cedar Creek manganese mining district is in the southwestern part of Frederick County and the northwestern part of Shenandoah County, Virginia. The manganese ore consists chiefly of the oxides pyrolusite and psilomelane, and forms replacement pockets and fracture fillings in the Oriskany sandstone and in residual sandy clay and chert derived from the New Scotland limestone. Both these formations are of Devonian age, and both form low ridges. The minable bodies have been deposited by ground water in the zone of weathering, and most of them lie above present ground-water level. The manganese-bearing formations, together with the older and younger formations exposed in Cedar Creek Valley, have been compressed into numerous folds, and at the southwestern end of the district one of these folds passes into a normal fault with a displacement of 1,000 feet or more.

From abstract: Mica has been mined in New Hampshire since 1803. Production from 1908 through 1939 has aggregated 13,326,990 pounds of sheet and punch mica, an annual average of 416,470 pounds. Since 1931 production has been below this average, because of economic conditions rather than depletions. The mica-bearing pegmatites of the Grafton and Keene districts occur mostly in sillimanite-mica schist adjacent to large areas of biotite gneiss. The pegmatite bodies range from a fraction of an inch to more than 200 feet in thickness; most of them are crosscutting, and about 75 percent strike northeast. Mica occurs sporadically in most of them but where present in commercial quantities it is localized in one or more of the following zones: (1) In quartz-plagioclase-muscovite zones 2 to 10 feet from the walls of large pegmatite bodies, (2) in or near quartz masses that occur mostly near the centers of the bodies, (3) in thin dikes 5 to 15 feet thick or in similar offshoots from larger bodies, (4) within large pegmatite bodies, in more or less tabular streaks or zones composed principally of plagioclase, quartz, and muscovite.

From abstract: Tin and tungsten minerals occur in pegmatites and quartz veins at Silver Hill, in secs. 23 and 24, T. 24 N., R. 43 E., 11 miles southeast of Spokane, Wash.

Abstract: The northern, eastern, and southern parts of the Olympic Peninsula, Wash., contain many small deposits of manganese. Most of the deposits consist of complex manganese silicates with some carbonates, although 16,275 tons of hausmannite (Mn304) ore was mined at the Crescent mine during 1924-26. About a hundred tons of silicates have been mined from various properties, mainly for experimental purposes. Future production probably will not be large, because the silicate ores are of low grade and are difficult and expensive to treat. Moreover, most of the deposits are difficult of access, and most of the ore bodies are small isolated lenses and thin tabular bodies. The deposits are mostly in red limestone or red argillite near contacts with basalt, but a few of them are in basalt.