Ida Bell dike exogreisen deposit, Lost River Mine, Lost River Valley, Port Clarence Mining District, Nome Census Area, Alaska, USAi

Regional Level Types
Ida Bell dike exogreisen deposit	Mine
Lost River Mine	Mine
Lost River Valley	Basin
Port Clarence Mining District	Mining District
Nome Census Area	Census Area
Alaska	State
USA	Country

Location: The Lost River Mine area includes the Cassiterite dike exogreisen deposit (TE048), the Lost River Mine skarn deposit (TE049), the Lost River Mine endogreisen deposit (TE050), and the Ida Bell dike exogreisen deposit (TE051). The Ida Bell exogreisen deposit is located on the on the west side of Cassiterite Creek, one mile upstream of its confluence with Lost River (Sainsbury, 1969, plate 1). It is at an elevation of 400 to 500 feet. The Ida Bell is a felsic dike that trends northwest for about 2 miles from Lost River across Cassiterite Creek. It intersects the northwest-trending Cassiterite dike in the prospect area. This location was not identified separately by Cobb and Sainsbury (1972) although several relevant references were summarized by Cobb (1975) under the name 'Lost River'.
Geology: The Ida Bell prospect is developed within a 2-mile long, northwest-trending felsic dike in Ordovician limestone that is up to 55 feet wide but averages 28.5 feet in width where exposed in dozer trenches. At the surface, this dike intersects the Cassiterite dike at about 500 feet elevation on the low north-south trending divide between Cassiterite Creek and Lost River. The age of the mineralization is assumed to be related to the development of tin systems in the Lost River area and therefore Late Cretaceous, the age of the tin-mineralizing granites there (Hudson and Arth, 1983). Fine-grained, leucocratic granite collected from a Lost River Mine dump has been dated at 80.2 +/- 2.9 my (Hudson and Arth, 1983, p.769). Local greisen development and related veining has been overprinted by late kaolinization in most exposed areas. Greisen contains quartz, topaz, sericite, fluorite, and arsenopyrite. A USBM diamond drill hole that intersects the Ida Bell dike 483 feet below the surface intersection with the Cassiterite dike shows it to be 40 feet wide and to average 0.33% tin including a seven foot section of 1.13% tin (Sainsbury, 1964, p. 52). The available drill holes and trenches outline a 900 x 400 x 28.5 foot volume containing about 840,000 tons that averages 0.26% tin and less than 0.1% WO3. One part of this block, near the intersection with the Cassiterite dike, contains 60,000 tons of 1.06% tin (Sainsbury, 1964, p. 52). The more local greisen development in the Ida Bell dike, at least at the surface, contrasts with the more extensive greisen alteration of the Cassiterite dike to the east of Cassiterite Creek in the Lost River mine. However, this prospect has not been extensively explored.
Workings: Several surface dozer trenches and four USBM diamond drill holes have been completed on the Ida Bell prospect. A short adit and winze were also developed (Heide, 1946, figure 2).
Age: The age of the mineralization is assumed to be related to the development of tin systems in the Lost River area and therefore Late Cretaceous, the age of the tin-mineralizing granites there (Hudson and Arth, 1983). Fine-grained, leucocratic granite collected from a Lost River Mine dump has been dated at 80.2 +/- 2.9 my (Hudson and Arth, 1983, p.769).
Alteration: Significant alteration is restricted to the Ida Bell dike and includes greisen (quartz, topaz, sericite, fluorite, tourmaline, and arsenopyrite replacement of granite) and later overprinting kaolinization.
Production: Production from the Lost River Mine has been from the Cassiterite dike exogreisen deposit (TE048).
Reserves: The available drill holes and trenches outline a 900 x 400 x 28.5 foot volume containing about 840,000 tons that averages 0.26% tin and less than 0.1% WO3. One part of this block, near the intersection with the Cassiterite dike, contains 60,000 tons of 1.06% tin (Sainsbury, 1964, p. 52).

Commodities (Major) - Sn, W
Development Status: None
Deposit Model: Exogreisen. This deposit has characteristics of both the tin vein model (15b) a

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Link to USGS - Alaska:	TE051

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References