• Phaneritic texture -- granite: interlocking grains typical of rocks that have cooled from a melt
• Phaneritic texture -- dunite: photomicrograph (in polarized light) of interlocking grains in an igneous rock
• Phaneritic texture-- granite: This is a plutonic (or intrusive) igneous rock. The large interlocking crystal grains indicate slow cooling deep below the earth's surface
• Aphanitic texture -- basalt: This is a volcanic (or extrusive) igneous rock. The grains are too small to recognize, indicating very rapid cooling at or very near the earth's surface
• Porphyritic texture -- andesite: This is an extrusive igneous rock. The magma from which it formed cooled slowly for a while deep below the surface (forming the large crystals), then finished cooling very quickly when it was ejected at the surface, forming the fine-grained groundmass.
• Vesicular texture -- basalt scoria: This is an extrusive igneous rock that chilled very quickly, so that the bubbles (vesicles) formed by escaping gas were preserved.
• Glassy texture -- obsidian: This is an extrusive igneous rock in which a viscous high-silica magma cooled so rapidly that no crystals had a chance to form
• Pyroclastic texture -- rhyolite tuff: This is an extrusive rock formed by fragments of hot volcanic rock and crystals blasted out of a volcano and welded together by the heat after the particles came to rest.
• Magma types and characteristics -- table showing silica content and rock types
• Silicic minerals -- light colored minerals high in silica and light metals
• Mafic minerals -- dark colored minerals low in silica, high in iron and magnesium
• Granite -- light-colored, phaneritic, high silica plutonic rock
• Pumice -- light colored, vesicular, high silica volcanic rock
• Rhyolite tuff -- light colored, pyroclastic, high silica volcanic rock
• Obsidian -- glassy, high-silica volcanic rock
• Diorite -- medium colored, phaneritic, intermediate silica plutonic rock
• Andesite -- medium colored, aphanitic, intermediate silica plutonic rock
• Gabbro -- dark colored, phaneritic, low-silica plutonic rock
• Basalt -- dark colored, aphanitic, low-silica volcanic rock
• Scoria -- dark colored, vesicular, low-silica volcanic rock
• Comparison of granite, diorite, and gabbro colors

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