igneous
Weathered feldspar-rich rock, possibly amazonite-bearing granite
Likely granite or pegmatite containing microcline feldspar (KAlSi₃O₈), with quartz and altered minerals
AI-generated identification · may be incorrectCoarse, irregular specimen with pale blue-green and tan coloring, dull to vitreous luster, and visible cleavage-like feldspar surfaces. Feldspar hardness is about Mohs 6–6.5; specific gravity roughly 2.55–2.75. Exact identification is uncertain from the image alone.
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Physical properties
Coarse, irregular specimen with pale blue-green and tan coloring, dull to vitreous luster, and visible cleavage-like feldspar surfaces. Feldspar hardness is about Mohs 6–6.5; specific gravity roughly 2.55–2.75. Exact identification is uncertain from the image alone.
Formation & geological history
Likely crystallized slowly from silica-rich magma in a continental igneous body or pegmatite, generally Precambrian to Phanerozoic in age, then weathered or altered near the surface.
Uses & applications
Used mainly as a lapidary, decorative, or teaching specimen; feldspar-rich granite is also used for aggregate, dimension stone, and ceramics.
Geological facts
Blue-green microcline is commonly called amazonite and derives its color from trace lead or related lattice defects. The apparent green-blue areas may instead be altered feldspar or another mineral.
Field identification & locations
Look for interlocking coarse grains, feldspar cleavage, and quartz’s glassy, non-cleaving appearance; a hardness test and streak/chemical examination would help distinguish amazonite from altered rock. Common sources include Colorado, Brazil, Madagascar, and Russia.
