sample petrography

sample petrography - Accessory minerals: Opaques (1%),...

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A- Hand Specimen Description Sample #: UTM-1 Color and color index: Leucocratic C.I.: 12 Average grain size (overall): Coarse grained . General texture: Holocrystalline; equigranular hypidiomorphic Mineralogy: (a) Essential Minerals: K-feldspar (35%), Plagioclase feldspar (25%), Quartz (20%), Hornblende (10%), Biotite: 7% (b) Secondary minerals: Chlorite (3%), Kaolinite (tr). Name: Granite B- Thin section description: Sample UTM-1 Mineralogy: Essential Minerals: Orthoclase (35%): Coarse grained (av. 1 cm) subhedral crystals with irregular stringers of Plag, and inclusions of Quartz. Plagioclase feldspar (25%): Coarse (8 mm) subhedral crystals that are slightly altered to kaolinite. Quartz (20%): Medium grained (0.5 mm) anhedral crystals often included in Orthoclase. Hornblende (7%): Medium grained suhedral crystals with inclusions of apatite. Biotite: (7%): Medium grained reddish brown (Ti-rich?) strongly pleochroic crystals with inclusions of zircon marked by pleochroic haloes. Altered along the rim to Chlorite.
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Unformatted text preview: Accessory minerals: Opaques (1%), Apatite (2%), Zircon (traces) Secondary minerals: Chlorite (3%): fine-grained subhedral crystals forming along the rims of biotite. Characterized by anomalous blue interference colors (Fe-rich?). Kaolinite (tr): forming at the expense of the orthoclase. Average Grain Size : Coarse grained General Texture : Equigranular hypidiomorphic Other textures: 1- Perthitic: 2- Graphic texture defined by the intergrowth between K-spar and Qz 3- Reaction rim texture: Bt → Chl 4- Myrmekitic texture defined by wormy inclusions of Qz in Plag next to Orth. Order of Crystallization: 1- Apatite and zircon: (euhedral inclusions in Hb & Bt) 2- Hb + Plag 3- Bt + Plag (cont.) + Opaque 4- K-spar + Qz 5- Secondary Chl after Bt 6- Plag altered to kaolinite. Full Rock Name: Coarse – grained, equigranular hypidiomorphic Hb – Bt granite with a graphic texture....
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This note was uploaded on 02/28/2012 for the course GLY 421 taught by Professor Staff during the Fall '11 term at Marshall.

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sample petrography - Accessory minerals: Opaques (1%),...

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