Southeast Ultramafics Cr-Mg; Blue Ridge belt

Region East, Southeast
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Several alpine-type ultramafic bodies occur in the eastern Blue Ridge of North Carolina. These bodies have been mined and prospected for olivine and chromite along with several other secondary or tertiary products, including magnesite as product of olivine alteration. Several ultramafic bodies occur in the Ashe Metamorphic Suite (Zatm), and others occur in migmatitic biotite gneiss (Ymg).
Identified resources Historical production magnesite.
Production Unknown.
Status Past mining.
Estimated resources Unknown.
Geologic maps Hadley and Nelson (1971), scale 1:250,000; Merschat and Cattanach (2008), scale 1:100,000; Southworth and others (2012), scale 1:100,000; Brobst (1962), scale 1:24,000; Merschat (1993, 1997, 2009), scale 1:24,000; Cyphers (2009), scale 1:24,000; Quinn (1991), scale 1:24,000; Hopson (1984), scale 1:24,000; Hatcher (1980), scale 1:24,000.
Geophysical data Inadequate Rank 4 aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Mines and prospects typically contain chromite, olivine, and magnesite. Peridotite and dunite in the Blue Ridge have been serpentinized, producing magnesite from alteration of olivine.
Deposits There are 20 magnesite occurrences in the belt of historical olivine and chromite mines, including Balsam Gap mine (MRDS dep_id: 10200034), Dark Ridge olivine deposit (MRDS dep_id: 10175907), Blanton Branch olivine mine (MRDS dep_id: 10296990), Cane Creek olivine deposit (MRDS dep_id: 10248543).
Evidence from mineral occurrences MRDS.
Geochemical evidence Favorable mineralogy and rock type.
Geophysical evidence Unknown.
Evidence from other sources See Raymond, Swanson and others (2003).
Comments Commodities include olivine, chromium, magnesium, asbestos, talc-soapstone, manganese, anthophyllite, and serpentine.
Cover thickness and description Cover less than 10 m.
Authors Arthur J. Merschat, Bernard E. Hubbard.
New data needs Geophysical data, geologic mapping, and geochemical analyses.
Geologic mapping and modeling needs Detailed maps of some ultramafic bodies.
Geophysical survey and modeling needs High resolution aeromagnetic and aeroradiometric coverage. Aeromagnetic data expected to image mafic rocks and associated structures, radiometric data can help with geologic mapping in vegetated terrane.
Digital elevation data needs Lidar adequate.