Flashcards
Geology- Igneous textures
Cards in this deck (13)
- 1EuhedralWell formed, sharp well recognisable faces.
- 2SubhedralMinerals grow close together, crystals are not fully formed
- 3AnhedralCrystals that fill in, groundmass
- 4EqugranularCrystals that are roughly the same size.
- 5PorphyriticLarge crystals (phenocrysts), have longer to grow, usually found in rapidly cooled ground-mass.
- 6PhenocrystsLarger crystals grow in the magma chamber,lava erupts, ground-mass rapidly cools, phynocrysts found within
- 7Phenocrysts- Intrusive rocksAt depth early crystals are formed or high concentration of mineral, larger crystals are allowed to form. As the magma rises cools at a faster rate so other crystals are smaller.
- 8Vesicular TextureLava that cools trapping gas bubbles within, leaving holes in the lava as it cools. Tend to form in the top of lava flows. Most extreme Pumices 99% porosity
- 9AmygdalodialViscous lavas have been in filled by the secondary growth of crystal, Common minerals are quartz,chlorites
- 10GlassyCooling is so rapid that crystals do not have time to form, Volcanic glass or obsidian.
Fractures concoridally - 11OphiticOne mineral cools around around smaller crystals, occurs when there is a certain concentration of minerals, they grow and then joint together. Usually Auginte which grows around feldspars
- 12Corona StructureOccur when melt is is disequilibrium with the soild. The central core is olivine and reacts on the outer edge producing layers of Pryroxine and Amphibole. Runs in line with Bowen's reaction series
- 13Flow BandingSilicic lavas such as ryolite are erupted at a lower temp than basalt, means they flow slowe, and commonly create flow banding.
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- Flashcards on Geology- Igneous textures, created by holliebishop1996 on 05/03/2014.
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- holliebishop1996
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