R 1827 Hornblende Andesite

Title: R 1827 Hornblende Andesite
Description: MEGASCOPIC: shows black hornblende crystals sprinkled in a light-gray groundmass
MICROSCOPIC: strongly zoned intermediate plagioclase forms phenocrysts and microphenocrysts. Oxyhornblende phenocrysts have generally narrow reaction rims of a very fine magnetite and pyroxene. A few microphenocrysts of the amphibole are entirely covered and some are corroded and segmentally veined by matrix material. The fine-grained matrix is composed of plagioclase microlites in a slightly fluidal pattern, minut prisms of clinopyroxene and dots of magnetite.
Source: Ward's Collection of Classic North American Rocks
Contributor: Hana Isihara
Identifier: R1827 Hornblende Andesite
Mediator: Tamara Carley (carleyt@lafayette.edu)
Rights Holder: Lafayette College Department of Geology and Environmental Geoscience

Media: https://exhibits.lafayette.edu/geology/files/original/d96e7a718b2ca5833f12e103b1cfa49b.jpeg; https://exhibits.lafayette.edu/geology/files/original/2d7109391d19555b15a6cd83bd15be24.jpeg; https://exhibits.lafayette.edu/geology/files/original/ff1112fe6a2f142039c34ec2f9ccf37a.jpeg; https://exhibits.lafayette.edu/geology/files/original/44615f687ba109e4f138d91c780f94e9.jpeg; https://exhibits.lafayette.edu/geology/files/original/b5b722498d403698d3790003b2d80566.jpeg; https://exhibits.lafayette.edu/geology/files/original/3b49f3fe1d74eb86e9a0d58024d8d9fa.jpeg; https://exhibits.lafayette.edu/geology/files/original/3ccaeced2fd213c0d954f59d81bfe7cf.jpeg; https://exhibits.lafayette.edu/geology/files/original/a1eaab15b41a316a5f2904adebb6b02d.jpg; https://exhibits.lafayette.edu/geology/files/original/7dac427ced043e28187a09ff840f3b11.jpg; https://exhibits.lafayette.edu/geology/files/original/3877d48ce94dd34736965db3b89510ca.jpg; https://exhibits.lafayette.edu/geology/files/original/50bea5adc531d05bba4be7fc2f7da018.jpeg; https://exhibits.lafayette.edu/geology/files/original/908e27c4620a5338fcaa2c2df73ac72a.jpeg