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Geology

Glassy Texture

Igneous Rock Textures

Glassy (or hyaline or vitreous) rocks have no or almost no grains at all, as in this quickly chilled pahoehoe basalt or in obsidian.
No visible grains
Photo (c) 2007 Andrew Alden, licensed to About.com (fair use policy)

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Gallery Index: Igneous Rock Textures

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