metamorphic
Unakite
Unakite (altered granite containing Epidote, Orthoclase, and Quartz)
Hardness: 6-7 (Mohs), Color: Pistachio green with pink and gray patches, Luster: Vitreous to dull, Crystal Structure: Monoclinic/Hexagonal (as a rock aggregate), Cleavage: None (fractures irregularly)
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Physical properties
Hardness: 6-7 (Mohs), Color: Pistachio green with pink and gray patches, Luster: Vitreous to dull, Crystal Structure: Monoclinic/Hexagonal (as a rock aggregate), Cleavage: None (fractures irregularly)
Formation & geological history
Formed through slow hydrothermal metamorphism where granite is altered by hot fluids, replacing plagioclase with epidote. Primarily Precambrian in age.
Uses & applications
Used for carvings, lapidary cabochons, beads, decorative architectural stone, and as a popular semi-precious gemstone for jewelry.
Geological facts
It was first discovered in the Unaka Range of the Appalachian Mountains in the United States and is the state rock of Virginia.
Field identification & locations
Identify by the unique 'pistachio and salmon' color combination. Common in riverbeds of the Blue Ridge Mountains and glacial drift around the Great Lakes. Useful for beginners due to its distinctive appearance.
