Peninsular Ranges pegmatites

Region West, Southwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area MRDS producers; Jahns and Wright (1951); Foley, Jaskula, Piatak and Schulte (2017).
Identified resources Historical production of beryllium (beryl), and lithium (lepidolite); production of spodumene, and tourmaline for gemstones.
Production Stewart mine produced 23,480 short tons of lepidolite between 1900 and 1929 (Jahns and Wright, 1951).
Status Past mining of gem-quality spodumene, lepidolite, and tourmaline.
Estimated resources Unknown.
Geologic maps Jennings and others (2010), scale 1:750,000; Rogers (1965), scale 1:250,000; Kennedy (1999), scale 1:24,000; Kennedy (2000a, b, 2003, 2006); scale 1:24,000; Tan (2000), scale 1:24,000; Tan and Kennedy (1999, 2003), scale 1:24,000; Dibblee and Ehrenspeck (1987), scale 1:24,000; Hernandez and others (2007), scale 1:24,000; Todd and others (2006), scale 1:24,000.
Geophysical data Inadequate Rank 3 aeromagnetic and Rank 5 aeroradiometric coverage.
Favorable rocks and structures Visible beryl, spodumene, and lepidolite in pegmatites in Cretaceous granite.
Deposits Stewart mine (MRDS dep_id: 10286994), Pala Chief Group (MRDS dep_id: 10077343), Rincon pegmatite district (MRDS dep_id: 60000262), Clark Extension prospect (MRDS dep_id: 10286855).
Evidence from mineral occurrences MRDS.
Geochemical evidence Visible beryl, gem quality spodumene and lepidolite.
Geophysical evidence None.
Evidence from other sources Jahns and Wright (1951); Hanley (1951).
Comments Recent 1:24:000 scale mapping covers a sizeable portion of the focus area given its proximity to large urbanized areas and active faults. Future efforts to understand these scattered gem-grade deposits could be focused on geochemistry of the various deposits and age dating.
Cover thickness and description Pegmatites exposed at surface.
Authors David A. Ponce, Amy Tuzzolino, Erica Key.
New data needs Updated geologic mapping, lidar, geochemistry, aeromagnetic and aeroradiometric surveys.
Geologic mapping and modeling needs Updated geologic mapping.
Geophysical survey and modeling needs High-resolution, Rank 1 aeromagnetic and aeroradiometric surveys.
Digital elevation data needs Lidar complete for part of focus area; incomplete over remainder.