IGNEOUS ROCK
CHART
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Muscovite |
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K-Feldspar |
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Quartz |
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Biotite |
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Amphibole |
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Mg-Pyroxene |
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Mg Olivine | |||||||||
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Na-Plagioclase
Na-Ca Plagioclase
Ca-Plagioclase |
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Temperature 600 700 800 900 1000 1100 1200
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Peridotite Family | ||||||
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Gabbro Basalt Family |
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Diorite-Andesite Family |
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Granite-Rhyolite Family |
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General Color |
Light |
Intermediate |
Dark |
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Chemistry |
Acidic/Felsic |
Intermediate |
Basic/Mafic |
Ultrabasic/Ultramafic | ||||
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Composition Þ Texture ß |
10-35%
Quartz Feldspar (25%-65% mostly
orthoclase) <20% Ferromagnesian metals (mostly biotite and/or
hornblende) |
<5%
Quartz 25%-65% Feldspar (mostly
plagioclase) 15%-35% Ferromagnesian minerals (mostly hornblende, minor
biotite, and/or pyroxene) |
No
Quartz 25%-50% Feldspar (only
plagioclase) 40%-80% Ferromagnesian minerals (mostly pyroxene and/or
olivine, minor hornblende) |
All plagioclase feldspar
and ferromagnesian minerals (If mostly olivine is Dunite, mostly pyroxene is Pyroxenite) | ||||
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Pegmatitic |
Pegmatitic Granite |
Pegmatitic Diorite |
Pegmatitic Gabbro |
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Phaneritic |
Granite |
Diorite |
Gabbro |
Dunite/Pyroxenite | ||||
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Porphyritic |
Prophyritic Granite/ Porphyritic Rhyolite |
Poprphyritic Diorite/ Poprphyritic
Andesite |
Poprphyritic Gabbro/ Poprphyritic Basalt |
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Aphanitic |
Rhyolite |
Andesite |
Basalt |
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Pyroclastic texture consists of broken angular
fragments of rock material in pyroclastic rocks. The fragmented material is composed of
pumice, glass, droplets of lava, and broken crystals. Some sorting and stratification are
generally present. Material finer
than 4 mm is known as Tuff. Material larger than 4 mm is referred to
as volcanic breccia or agglomerate.
Glassy texture is similar to that of
ordinary glass. No crystals are
present therefore no minerals are present even when the specimen is viewed under
magnification. A specimen with
glassy texture also has a dark color and glassy appearance: Obsidian.
Vesicular Texture specimens are
filled with
air bubbles. If the specimen is
light in color it is named Pumice; if dark, it is named
Scoria.