metamorphic
Unakite
Epidotized Granite (SiO2 with Ca2(Al, Fe)3(SiO4)3(OH))
Hardness: 6-7 (Mohs scale); Color: Mottled green (epidote), pink (orthoclase feldspar), and clear/grey (quartz); Luster: Vitreous to dull; Crystal structure: Monoclinic/Triclinic mixture; Cleavage: None/Irregular fracture; Specific gravity: 2.85-3.20.
- 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 clear/grey (quartz); Luster: Vitreous to dull; Crystal structure: Monoclinic/Triclinic mixture; Cleavage: None/Irregular fracture; Specific gravity: 2.85-3.20.
Formation & geological history
Formed through the hydrothermal metamorphism of granite, where plagioclase feldspar is replaced by epidote. Usually associated with Proterozoic era geological formations.
Uses & applications
Used primarily as a decorative stone, in lapidary work for cabochons and beads, and occasionally as architectural stone or floor tiles.
Geological facts
First discovered in the Unaka Range of North Carolina, USA. It is often found as river pebbles and is the unofficial state rock of Virginia.
Field identification & locations
Identify in the field by its distinct 'pistachio' green and salmon pink color combination. It is commonly found in Blue Ridge Mountains and Lake Superior shorelines. Collectors should look for balanced color distribution.
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