metamorphic
Polished/tumbled unakite (probable)
Unakite; epidote + pink potassium feldspar + quartz
AI-generated identification · may be incorrectTypically mottled pistachio-green and salmon-pink, with a dull to vitreous luster and no obvious cleavage on a tumbled surface. Hardness is about 6–7 Mohs; specific gravity approximately 2.7–3.3. The specimen’s rounded, polished form and color pattern fit unakite, though lighting limits certainty.
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Physical properties
Typically mottled pistachio-green and salmon-pink, with a dull to vitreous luster and no obvious cleavage on a tumbled surface. Hardness is about 6–7 Mohs; specific gravity approximately 2.7–3.3. The specimen’s rounded, polished form and color pattern fit unakite, though lighting limits certainty.
Formation & geological history
Unakite forms when granitic rock undergoes hydrothermal alteration, replacing minerals with epidote while preserving pink feldspar and quartz. Classic material comes from the Unaka Mountains of North Carolina/Tennessee; the reported Rochester-area location is not a classic source, so local glacial transport or imported lapidary material is more likely.
Uses & applications
Used as inexpensive cabochons, beads, carvings, tumbled stones, and decorative pieces; it has little industrial use.
Geological facts
Its characteristic green-and-pink pattern results from epidote replacing dark minerals and feldspar in altered granite. It is often sold in polished form rather than as fresh outcrop material.
Field identification & locations
Look for a coarse, interlocking pink-green pattern, hardness near quartz, and resistance to scratching by a steel knife. Common sources include the southeastern United States and various gravel deposits; confirm with a streak, hardness, and magnification test.
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