metamorphic
Unakite
Unakite (Metasomatized Granite)
Hardness: 6.0-7.0 (Mohs); Color: Mottled green (epidote), pink (orthoclase feldspar), and clear/grey (quartz); Luster: Vitreous to pearly; Crystal structure: Monoclinic and hexagonal; Cleavage: None (fractures); Specific gravity: 2.85-3.20.
- Hardness
- 6
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6.0-7.0 (Mohs); Color: Mottled green (epidote), pink (orthoclase feldspar), and clear/grey (quartz); Luster: Vitreous to pearly; Crystal structure: Monoclinic and hexagonal; Cleavage: None (fractures); Specific gravity: 2.85-3.20.
Formation & geological history
Formed through the hydrothermal metamorphism of granite, where plagioclase feldspar is replaced by epidote through metasomatism. It dates back to various tectonic events, often orogenic (mountain-building) periods.
Uses & applications
Commonly used as a decorative stone, for carving figurines (like the animal shown), lapidary work (cabochons and beads), and occasionally as architectural facing stone or floor tiles.
Geological facts
It was first discovered in the Unaka Range of the Appalachian Mountains in North Carolina/Tennessee, USA, for which it is named. Unlike many gemstones, it is a rock composed of three distinct minerals rather than a single mineral species.
Field identification & locations
Identify by its unique 'pistachio green and salmon pink' mottled appearance. It is found in river beds and beach gravel, notably along Lake Superior. Collectors look for a balanced distribution of colors without excessive fractures.
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