Geologic description
The Olsen prospect consists of two long-abandoned shafts sunk on the east side of Anvil Creek. The workings date from the early 1900s (Mertie, 1918 [B 662-I, p. 425-449]; Cathcart, 1922). A 54-foot shaft was sunk on a north-northwest striking, west-dipping quartz vein. According to the owner, Charles Olsen, the shaft struck stibnite ore at 49 feet and was in stibnite-bearing rock to abandonment of the shaft at 54 feet. A 97-foot shaft was sunk nearby. It reportedly encountered stibnite-bearing ore at 60 feet that continued on the hanging wall of a vein to the bottom of the shaft; the shaft was abandoned due to flooding. Material observed on the dump included finely crystalline stibnite with quartz and pyrite. The material reportedly assayed about 1 ounce of gold per ton, 2.05 dollars worth of silver, and some copper (Cathcart, 1922, p. 239-40). The veins reportedly had talc schist hanging walls about 10 feet thick. Mertie (1918 [B 662-I, p. 431-432]) believed that the veins were in a fault zone. He noted that graphitic schist walls were cut by nearly vertical quartz veins with a strike of N45E. The veins probably are in the Anvil fault zone as shown by Hummel (1962 [MF 247]), who mapped a wide graphitic zone between two main faults along this part of Anvil Creek. Where the Anvil fault is exposed in the Snake River road cut (NM234), the graphitic schist is highly sheared and contorted in a zone 100 feet wide and locally contains stibnite. |
