metamorphic
Unakite
Epidotized Granite
Hardness: 6-7 (Mohs scale); Color: Mottled green and pink; Luster: Vitreous to dull; Crystal structure: Monoclinic and Trigonal components; Cleavage: None (fractures); Specific Gravity: 2.85-3.20
- Hardness
- 6-7 (Mohs scale)
- Color
- Mottled green and pink
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Mottled green and pink; Luster: Vitreous to dull; Crystal structure: Monoclinic and Trigonal components; Cleavage: None (fractures); Specific Gravity: 2.85-3.20
Formation & geological history
Formed through the hydrothermal alteration of granite, where plagioclase feldspar is replaced by epidote. Usually associated with Precambrian or Paleozoic eras in metamorphic belts.
Uses & applications
Commonly used in lapidary work for cabochons, beads, and decorative carvings. Also used as a high-quality architectural stone and in construction as an ornamental aggregate.
Geological facts
It was first discovered in the Unaka Range of North Carolina, USA, for which it is named. It is unique among granites because it lacks the typical mica components, which are replaced by green epidote.
Field identification & locations
Identified by its distinctive 'pistachio green' epidote mixed with 'salmon pink' orthoclase feldspar. Commonly found in riverbeds in the Blue Ridge Mountains and as glacial drift in the Great Lakes region.
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