Introductory Geology - Crystalline Rock Textures




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These photographs are of crystalline rocks, which are composed of crystals that grew together in an interlocking manner, like when a magma cools and solidifies. The bottom photograph is of a rock that is too fine to tell, without a microscope, whether it is composed of clasts or crystals.

Click on a small photo to the left to bring up a larger version.

catalina_peg.jpg (37585 bytes) Finely crystalline rocks (granite) cut by dikes of coarsely crystalline rock (granitic pegmatite), Santa Catalina Mountains, Arizona
kitt_peak.jpg (35000 bytes) Coarsely crystalline rock (granite), Kitt Peak, Arizona
porph_granite.jpg (47816 bytes) Coarsely crystalline rock (granite) containing a dark inclusion of older finely crystalline rock, Harquahala Mountains, Arizona
granite_wash.jpg (72415 bytes) Medium-crystalline rock (granodiorite) containing a dark inclusion of older, finely crystalline rock, Granite Wash Mountains, Arizona
ajo_childs.jpg (39631 bytes) Coarse crystals in a finely crystalline to glassy matrix, Ajo, Arizona
bonito_vessicles.jpg (39478 bytes) Very finely crystalline to glassy (too fine to tell) rock (basalt with holes or vesicles) from a volcanic eruption in 1057 AD, Sunset Crater, Arizona