Igneous Rock Textures 4.0 / 5 based on 1 rating ? AllUniversityAll boards Created by: Jason BrowneCreated on: 22-04-13 04:15 Holocrystaline Wholly crystalline. 1 of 29 Hemicrystaline Partly crystals and partly glass 2 of 29 Holohyaline Wholly Glass 3 of 29 Phaneritic coarse crystals are visible without a microscope. Indicate slow cooling 4 of 29 Phaneritic-Fine Grained particles less than 1mm in diameter 5 of 29 Phaneritic-Medium Grained particles between 2-5mm in diameter 6 of 29 Phaneritic-Course Grained particles are 5mm or more in diameter 7 of 29 Aphanitic fine texture where crystals are only visible under a microscope. Indicates rapid cooling. 8 of 29 Aphanitic-Lithoidal rock is stony or granular in appearance. 9 of 29 Aphaitic-Vitreous rock is shiny and glassy in appearance, but it not holohyaline. 10 of 29 Equigranular mineral grains are all roughly the same size 11 of 29 Porphyritic grains have a distinct contrast in size. 12 of 29 Seriate minerals show a gradation in grain size. Goes from small to large. 13 of 29 Massive rock is uniform in appearance showing no real structural features. 14 of 29 Pegmatitic very course grained. 15 of 29 Vesticular rock contains cavities (vesticles). 16 of 29 Scoriaceous Rock is so vesticular that it has a spongey appearance 17 of 29 Amygdaloidal vesticles in rock are filled with a secondary mineral introduced after the consolidation of the rock. 18 of 29 Perlitic Rock contains many cracks due to the contraction during cooling. Normally formed in natural glass 19 of 29 Spherulitic body is composed of spherical bodies 20 of 29 Melenocratic 60%-100% dark 21 of 29 Mesocratic 30-60% dark minerals 22 of 29 Leauocratic 0-30% dark minerals 23 of 29 Felcic/Acidic Rock rocks dominated by light coloured minerals. Rock normally dominated by quarts, feldspars and muscovites. 24 of 29 Mafic/Basic Rocks Rocks dominated by dark coloured minerals. 25 of 29 Extrusive Igneous rocks that have breached the Earths surface. 26 of 29 Tephra Pieces ejected from a volcanic eruption. 27 of 29 Bomb a pyroclast whose composition indicated ejection as a magama. 28 of 29 Black a pyroclast which composition indicates ejection as a solid. 29 of 29
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