metamorphic
Unakite
Epidote–pink feldspar–quartz rock
AI-generated identification · may be incorrectTypically green epidote, salmon-pink orthoclase or microcline feldspar, and gray to clear quartz in a granular, crystalline texture. Hardness is about 6–7 Mohs; luster is generally vitreous to dull, with no prominent cleavage in the whole rock and specific gravity around 2.8–3.2.
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Physical properties
Typically green epidote, salmon-pink orthoclase or microcline feldspar, and gray to clear quartz in a granular, crystalline texture. Hardness is about 6–7 Mohs; luster is generally vitreous to dull, with no prominent cleavage in the whole rock and specific gravity around 2.8–3.2.
Formation & geological history
Forms when granite undergoes hydrothermal alteration or low-grade metamorphism, replacing some feldspar with epidote while preserving the original texture. Classic unakite formed in the Appalachian region during Paleozoic tectonic events, although similar rocks occur elsewhere.
Uses & applications
Used as tumbled stones, cabochons, beads, carvings, decorative aggregate, and ornamental stone; it has little industrial value.
Geological facts
Its distinctive pink-and-green pattern results from contrasting feldspar and epidote, while quartz commonly forms the gray or translucent matrix.
Field identification & locations
Identify it by the mottled salmon-pink, pistachio-green, and gray crystalline appearance; it is commonly collected in river gravels and exposed altered granite, especially in the eastern United States, South Africa, Brazil, and China.
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