metamorphic
Unakite
Unakite (altered granitic rock: SiO2 + Ca2(Al,Fe)3(SiO4)3(OH))
Hardness: 6–7 Mohs; Color: Mottled green, pink, and orange-red; Luster: Vitreous to dull; Crystal structure: Monoclinic/Triclinic components; Cleavage: None; Specific gravity: 2.85–3.20
- Hardness
- 6–7 Mohs
- Color
- Mottled green, pink, and orange-red
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6–7 Mohs; Color: Mottled green, pink, and orange-red; Luster: Vitreous to dull; Crystal structure: Monoclinic/Triclinic components; Cleavage: None; Specific gravity: 2.85–3.20
Formation & geological history
Formed via hydrothermal metamorphism of granite where plagioclase feldspar is replaced by epidemic. Typically found in Precambrian terrains or as pebbles in riverbeds.
Uses & applications
Primary use in jewelry for beads, cabochons, and carvings. Also used in construction as an ornamental stone and architecture facing.
Geological facts
First discovered in the Unaka Range of the Appalachian Mountains in the United States, which gave it its name. It is the state rock of Virginia.
Field identification & locations
Identify by its distinctive combination of pistachio-green epidote and salmon-pink orthoclase feldspar. Commonly found in the Blue Ridge Mountains of the USA and in river deposits in the Great Lakes region.
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