| Basis for focus area |
Topsham district of Cameron and others (1954); extended district to include Larrabee deposit. |
| Identified resources |
Historical production of beryllium (beryl), feldspar, and mica. |
| Production |
Unknown. |
| Status |
Past mining. |
| Estimated resources |
Unknown. |
| Geologic maps |
Hussey and Marvinney (2002), scale 1:100,000; Hussey and West (2018), scale 1:24,000; West and Hussey (2020), scale 1:24,000; West (2019), scale 1:24,000. |
| Geophysical data |
Inadequate Rank 5 aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Pegmatite cutting granite. |
| Deposits |
Coombs feldspar quarry (MRDS dep_id: 10107755), Todd mine (MRDS dep_id: 10291536), McKay Farm prospect (MRDS dep_id: 10291300) Consolidated quarries (MRDS dep_id: 10194708), Fisher quarry (MRDS dep_id: 10242337), Golding's quarry (MRDS dep_id: 10242241), Rumrill, William Willes, Trufant, Alice Staples, Larrabee. |
| Evidence from mineral occurrences |
MRDS. |
| Geochemical evidence |
Favorable mineralogy and rock type. |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Unknown. |
| Comments |
It is reported that masses of columbite-tantalite weighing as much as 15 lbs were recovered from the Coombs mine (Cameron and others, 1954). |
| Cover thickness and description |
Variable limited cover and glacial cover estimated at less than 2-50 m. |
| Authors |
Gregory J. Walsh, Bernard E. Hubbard. |
| New data needs |
Modern maps at 1:24,000 scale and 1:100,000 scale show good coverage. Geochemical sampling needed. |
| Geologic mapping and modeling needs |
Additional mapping at 1:24,000 scale may be needed, geophysics may not be useful for pegmatites. |
| Geophysical survey and modeling needs |
High resolution aeromagnetic and aeroradiometric coverage can assist with framework geology such as structural features and contacts. |
| Digital elevation data needs |
Lidar complete. |
