San Gabriel Mountains anorthosite

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

Information leading to the delineation of this focus area

Basis for focus area San Gabriel Mountains anorthosite: Massif anorthosite permissive for Ti-V and (or) conduit-type Cu-Ni-PGE deposits.
Identified resources Identified resources for aluminum (anorthosite), REE, titanium, and vanadium. Historical production of titanium and vanadium.
Production Past production (pre-1950) for titanium (Benson and others, 1962).
Status V2O3 percent was 0.5%, but likely lower; 6 to 12 million short tons possible for identified magmatic titanium district with byproduct V; additional 2.74 million metric tonnes placer ilmenite resource (Benson and others, 1962).
Estimated resources Titanium: 4,800,000 tonnes, grade 12% TiO2; Aluminum: Anorthosite in the San Gabriel Mountains, Los Angeles and San Bernardino Counties, California, has been evaluated for Al resources and mined on a small scale for clay. It comprises a partially quantified “enormous reserve” of ~27% Al2O3. Small amounts of clay have been produced from weathered anorthosite for cement manufacture (Carter, 1982); REE: Ilmenite-magnetite-apatite-rich cumulate in anorthosite of the San Gabriel Mountains, Los Angeles and San Bernardino Counties, California, constitutes a low-grade REE resource (0.17% RE2O3) that could contain 2 Mst of RE2O3, about 16% of which is Y (Carter, 1982).
Geologic maps Dibblee (1996), scale 1:24,000; Campbell and others (2014), scale 1:100,000.
Geophysical data Inadequate Rank 3 aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Pyroxenite/ferrodiorite/anorthosite; As a group, massif-type anorthosites are permissive for Fe-Ti-V deposits. One conduit-type Cu-Ni-PGE deposit, Voiseys Bay, is associated with the Nain anorthosite province in Quebec. It is possible (but not likely) that magmatic sulfide deposits could be associated with the intrusion or its feeders.
Deposits San Gabriel Anorthosite (MRDS dep_id: 10236223); Iron Blossom Group (MRDS dep_id: 10211929); Lang 4 deposit (MRDS dep_id: 10260932).
Evidence from mineral occurrences MRDS.
Geochemical evidence None.
Geophysical evidence Unknown.
Evidence from other sources Unknown.
Comments The relationship (if any) between the anorthosite and allanite pegmatites in Pacoima Canyon is poorly understood (Neuerburg, 1954; Carter, 1980).
Cover thickness and description Anorthosite is exposed at surface. Placer titanium present and previously mined in Santa Clara river.
Authors Michael L. Zientek, Ben Parrish, 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 inadequate.