igneous
Tumbled pegmatitic rock, likely amazonite-bearing granite
Granite/pegmatite composed mainly of quartz, feldspar, and mica; blue-green area may be microcline (amazonite)
AI-generated identification · may be incorrectHardness about 6–7 (Mohs); coarse crystalline texture with gray-black, white, and pale blue-green zones, vitreous to dull luster, and no obvious cleavage on the polished surface. Exact identification is uncertain from the photograph alone.
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Physical properties
Hardness about 6–7 (Mohs); coarse crystalline texture with gray-black, white, and pale blue-green zones, vitreous to dull luster, and no obvious cleavage on the polished surface. Exact identification is uncertain from the photograph alone.
Formation & geological history
Formed by slow cooling of silica-rich magma, likely in a granitic pegmatite; such bodies commonly formed during Precambrian to younger continental mountain-building events. The rounded surface is human-tumbled and polished.
Uses & applications
Used as a decorative and lapidary stone, paperweight, or inexpensive specimen; amazonite-bearing material is sometimes cut into cabochons and beads.
Geological facts
The dark material may be biotite or amphibole, while the white material is likely quartz or feldspar. Color alone cannot confirm amazonite without examining crystal cleavage or testing mineral composition.
Field identification & locations
Common in granite and pegmatite regions, including Colorado, Madagascar, Brazil, and Russia. Look for interlocking grains, feldspar cleavage, quartz without cleavage, and a glass-scratching hardness.
