metamorphic
Unakite (Epidote-Rich Granite)
Unakite (Granite consisting of Orthoclase, Quartz, and Epidote)
Hardness: 6-7 (Mohs scale); Color: Mottled green (epidote), pink (orthoclase feldspar), and gray (quartz); Luster: Vitreous to dull; Crystal structure: Coarse-grained phaneritic structure; Cleavage: None (fractures irregularly); Specific gravity: 2.55-2.85.
- Hardness
- 6-7 (Mohs scale)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Mottled green (epidote), pink (orthoclase feldspar), and gray (quartz); Luster: Vitreous to dull; Crystal structure: Coarse-grained phaneritic structure; Cleavage: None (fractures irregularly); Specific gravity: 2.55-2.85.
Formation & geological history
Formed via the hydrothermal metamorphism of granite. This process occurs when hydrothermal fluids alter plagioclase feldspar into epidote while preserving pink orthoclase and quartz. They are typically found in ancient mountain belts.
Uses & applications
Commonly used as a decorative stone, in lapidary work for cabochons and beads in jewelry, and occasionally as architectural facing or floor tiles due to its durability and unique aesthetics.
Geological facts
Unakite is the state rock of Virginia, USA. It was named after the Unaka Range of the Blue Ridge Mountains where it was first discovered and described.
Field identification & locations
Identify in the field by its distinct 'Christmas' color scheme of salmon-pink and pistachio-green. It is commonly found in riverbeds and as pebbles along Lake Superior's shores and throughout the Appalachian Mountains.
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