| Basis for focus area |
Quartz veins with cassiterite up to 3 ft wide extending 1,000-2,000 ft in exposed granite outcrop. See Price and others (1983). |
| Identified resources |
Historical production of tin. |
| Production |
Eight tons of pure Sn metal was smelted in a small mill after ore was discovered in 1899. Production ceased in 1912 (Harbour, 1972, p. 76-77). |
| Status |
Small past mining operations. |
| Estimated resources |
Ore is of high quality, and the cassiterite is easily concentrated and smelted, but the veins are thin and lenticular, and the reserves may be small (Harbour, 1972). |
| Geologic maps |
Lucia (2010), scale 1:100,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Precambrian granite. |
| Deposits |
El Paso mine (MRDS dep_id: 10085695), Franklin Mountain tin deposits (MRDS dep_id: 10154673; USMIN Site_ID: TX00011). |
| Evidence from mineral occurrences |
MRDS; USMIN. |
| Geochemical evidence |
Ore consists of cassiterite in disseminated crystals and massive chunks in quartz veins and surrounding granite. The granite consists almost entirely of fine- to medium-grained quartz and orthoclase; cassiterite appears to replace both minerals. Scattered crystals of wolframite, fluorite, topaz, tourmaline, and pyrite are associated with ore (Harbour, 1972). |
| Geophysical evidence |
No data. |
| Evidence from other sources |
Old prospect data, and early 20th century prospecting. |
| Comments |
Only tin ore that has been mined commercially in the State of Texas. |
| Cover thickness and description |
Deposits may be present at the surface or at depth in mapped sedimentary rocks or concealed by Cenozoic basin fill. |
| Authors |
Brent A. Elliott, Laurel G. Woodruff. |
| New data needs |
New mapping, high resolution geophysics. |
| Geologic mapping and modeling needs |
Geologic mapping at a scale of 1:24,000. |
| Geophysical survey and modeling needs |
High resolution aeromagnetic survey would be useful for tracing subsurface geology and structures. |
| Digital elevation data needs |
Lidar adequate. |
