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Show 35 Rifle vanadium deposit or mine. The vanadium-mineralization resembles that of the Placerville area; roscoelite is the principal vanadium-bearing mineral and the ore horizon is in or near the base of the Entrada sandstone. Vanadium was reported on Rifle Creek in 1920, but the first recorded production was in 1926, when the deposit was acquired by the United States Vanadium Corporation which owns and operates the mine. In 1932, when the mine was closed down, several million pounds of vanadium had been produced from ore that averaged about two per cent V205 content. Vanadium mining was discontinued and the buildings at the mine, and the mill east of Rifle, were dismantled in 1932. The company has not made public its reason for stopping work in the Rifle mine, however, the writers consider it significant that the action of the^Company coincides with two important events, namely: (1) during the depression that started in 1929 the market for vanadium decreased and a large stock of unsold vanadium pentoxide (V2Q5) accumulated; and, (2) during 1928 and 1929 the United States Vanadium Corporation acquired the vanadium properties of the Standard Chemical Company in Southwestern Colorado. The Standard Chemical Company had been active in mining carnotite ore for its radium content prior to 1923 and in the course of mining and exploratory diamond drilling had developed substantial quantities of vanadium ore. In addition low-grade radium ore containing about two per cent V ^ had been stock-piled in the belief that eventually the vanadium would be valuable. The |
