Hand Sample: Aphanitic brown-black basalt with microcrystalline inclusions of quartz and alkali feldspar. Weathers to yellow orange. Part of a dike cross cutting granite at the Cornwall Quarry.
Thin Section, XPL: 15% medium-grained plagioclase crystals in 75% matrix of very-fine-grained opaques, plagioclase, and biotite. Very fine veins of a darker material run through the sample.
Western Minerals, Inc
Is Part Of
St. Francois Mtns. Batholith, Missouri Cornwell Quarry
Purchased from Western Minerals Inc.
Number of Thin Sections