LAB 5 terms

LAB 5 terms - a fine grained texture Phaneritic(crystals...

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Texture: description of its constituent parts and their sizes, shapes, and arrangement. Composition: Mafic: minerals such as Biotite mica, amphibole, pyroxene, and olivine are generally dark colored, the name referst he magnesium and iron in their chemical formulas. Felsic: have only 0%-15% MAFIC MINERAL CRYSTALS SO THEY ARE GENERALLY VERY LIGHT COLORED Intrusive: an intrusion that has cooled forming coarse-grained igneous rock comprised of visible mineral crystals. Extrusive: lava which cools to form a fine-grained igneous rock comprised of tiny crystals and/or glass Aphanitic: (crystals <1mm) rapid cooling, fluid lava, and/or good nucleation, igneous rocks comprised of crystals too small to see without a hand lens have
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Unformatted text preview: a fine grained texture Phaneritic: (crystals 1-10mm) slow cooling, viscous magma, and/or good nucleation (coarse-grained) Pegmatitic: (Crystals >1cm) very slow cooling, viscous magma, and/or good nucleation (very coarse-grained) Porphyritic: (large and small crystals) slow, then rapid cooling and/ or change in magma viscosity or composition. Glassy: rapid cooling and/or very poor nucleation Vesicular: rapid cooling of gas charged lava, gas bubbles in lava Pyroclastic: accumulations of rocky materials that have been fragmented and ejected by explosive volcanic eruptions...
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