Tungsten Hills

Project Summary

An estimated 100,000 tons of probable ore at 0.25–0.5% WO₃ in reserve across at least a dozen pendants, most of which have only been prospected at surface. District production exceeded 100,000 units of WO₃ from 1916 to 1945 with the largest producer (Little Sister) processing over 182,000 tons of ore alone. The Round Valley pendant—the largest and deepest in the district—extends several hundred feet below existing workings and was identified by USGS geologists as having the most promise for additional tonnage at depth. 40 lode claims totalling approximately 826 acres across two blocks covering seven known prospects in the Deep Canyon and Round Valley areas, Inyo County, California.

The project is located in the Tungsten Hills, approximately 10 miles west of Bishop, Inyo County, California. Access via unimproved roads from U.S. Hwy 395. Readily available electric power and water.

Deep Canyon Block: 34 lode claims (TH 1–34), 702.4 acres

Round Valley Block: 6 lode claims, ~124 acres, ~2.3 miles northwest of the Deep Canyon block

Geology

Contact-metamorphic scheelite deposits hosted in metamorphosed sedimentary roof pendants (schist, quartzite, limestone, and tactite) surrounded by Mesozoic granite and quartz diorite. Scheelite occurs as disseminations and irregular masses within garnet-epidote tactite where limestone strata were altered by intruding granitic magmas. Ore grades range from 0.25 to 1.0% WO₃, with individual specimens to 10% WO₃. The Deep Canyon pendant hosts the principal developed mines; the Round Valley pendant at the north edge of the hills is the largest in the district at approximately 4,000 feet long by 600–1,000 feet wide, with scheelite in at least five separate beds along its north granite contact.

History

Scheelite was discovered in August 1913 by placer gold miners on the Jackrabbit claim. Development began in 1916 when tungsten prices surged; Standard Tungsten Co. built a mill and developed the Aeroplane group while Tungsten Mines Co. commenced on 14 claims including the Little Sister and Jackrabbit, completing a 300-ton mill by mid-1916. At peak approximately 125 men were employed and "Tungsten City" was established in Deep Canyon. The Little Sister became the largest producer, processing over 182,000 tons. Operations wound down after 1919 when prices collapsed but resumed intermittently through the 1930s–40s with wartime demand. The Round Valley mine was discovered in 1917 and was actively producing into 1940; a DMEA exploration programme (DMEA-4614) was later conducted under government assistance. Total district production exceeded 100,000 units of WO₃, approximately 80% from Deep Canyon.

Prospects – Deep Canyon Block (34 Claims)

**Little Sister**

The largest individual producer in the district. Operated by Tungsten Mines Co. and later Bishop Tungsten Co. from 1916 to 1942, processing over 182,000 tons. The glory hole measures 300 ft long, 100 ft across, and 150 ft deep. Past recovery averaged slightly over 0.5% WO₃, though mill tailings recovery suggests the ore contained considerably more. Ore continued to the adit level and a winze was sunk in tactite beneath. Diamond drilling was planned to test the body at depth but was never completed. The tactite persists below the lower adit level and the deposit warrants further evaluation at depth.

**Aeroplane**

Two main ore bodies on the divide between Deep Creek and McGee Creek, operated by Standard Tungsten Co. 1916–1918 and 1942–1944. Developed by a large glory hole, 2 adits at 50 and 195 ft below outcrop, and a long adit to the north ore body. Production totalled 45,000 metric tons (1918) and 51,000 metric tons (1944). Undiscovered ore bodies may exist along strike in both directions.

**Lucky Strike**

South side of Deep Canyon, developed by 2 adits at 90 and 135 ft below outcrop and a glory hole. A single scheelite bed in tactite 10–20 ft thick dips gently south-eastward. The same ore bed appears along strike to the southwest in several prospects separated by quartz diorite, which may still contain ore.

**Jackrabbit**

Original discovery site of tungsten in the district (August 1913). Developed by two glory holes and a 200-ft main adit on a body of sediments approximately 280 ft long and 80 ft wide. Low-grade scheelite occurs along the entire contact with a considerable tonnage at approximately 0.1% WO₃; commercial ore bodies are possible through further prospecting.

**Tungsten Blue (Pappas)**

Past producer in NW, operated 1941–1944. Ore body nearly vertical, approximately 10 ft thick, extending nearly 100 ft northwestward in tactite. In 1944, 38,400 tons treated averaging 0.35–0.4% WO₃, yielding 27 wt% WO₃ concentrate.

**White Caps**

Past producer in, also known as the Little McGee Creek Mine. Ore body dips vertically, approximately 3 m thick and 24 m long. Produced 1941 and 1943–1944 via underground workings including a 135-ft adit. Dump material reported at 500 tons assaying 1% WO₃.

Round Valley Block (6 Claims)

**Round Valley Mine**

Located at the north edge of the Tungsten Hills within the largest roof pendant in the district, approximately 4,000 ft long and 600–1,000 ft wide. The most productive mine in the pendant, developed through three adits, a glory hole, and an inclined shaft 65 ft deep across three ore beds. The western ore body provided the main tonnage at 100 ft long and 20 ft wide, dipping 45° W. The adjacent Western Tungsten Co. mine developed a further ore body 200 ft long at surface via a 170-ft adit and 270 ft of drifts, with an estimated 25,000 tons above adit level. USGS geologists concluded that the pendant and favourable beds extend downward probably several hundred feet—deeper than any other in the district—and that additional ore bodies should be found at depth. This property is considered the best prospect in the area for further tonnage at depth.

Further information is available on request. Please feel free to get in touch with a member of our team, or fill out the form below.

Project Media