metamorphic
Green Quartzite (with Fuchsite)
Quartzite with Muscovite variety Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)
Hardness: 7 (Mohs scale), Color: Emerald green to light green with white/tan matrix, Luster: Vitreous to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 - 2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: Emerald green to light green with white/tan matrix, Luster: Vitreous to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 - 2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. The green coloration is caused by the presence of chromium-rich mica (fuchsite) within the quartz matrix. Most specimens date from the Proterozoic or Archean eras.
Uses & applications
Used primarily as decorative stone, in landscaping, as a gemstone for beads and cabochons (sometimes sold as 'Green Aventurine'), and as an ornamental building material.
Geological facts
When green quartzite contains enough mica to create a shimmering effect known as aventurescence, it is classified as Aventurine. The green color specifically comes from chromium replacing aluminum in the mica structure.
Field identification & locations
Identify in the field by its intense hardness (will scratch glass) and the presence of green micaceous specks or veins within a grainy, sugary-textured rock. It is commonly found in Brazil, India, and parts of the United States like the Appalachian Mountains.
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