metamorphic

Fuchsite Gneiss (Green Quartzite)

Chromium-rich Muscovite (KAl2(AlSi3O10)(OH)2 with Cr replacements)

AI-generated identification · may be incorrect

Hardness: 6-7 (if quartz-heavy) or 2-3 (if pure mica); Color: Emerald green to silvery-green; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect basal.

Hardness: 6-7 (if quartz-heavy) or 2-3 (if pure mica)
Color: Emerald green to silvery-green
Luster: Vitreous to pearly

Identified April 14, 2026More metamorphic →

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Physical properties

Hardness: 6-7 (if quartz-heavy) or 2-3 (if pure mica); Color: Emerald green to silvery-green; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect basal.

Formation & geological history

Formed through regional metamorphism of clay-rich sediments or ultra-mafic rocks where chromium is present. The green color is derived from small amounts of trivalent chromium replacing aluminum in the mica structure.

Uses & applications

Used primarily as an ornamental stone, in the production of 'Green Aventurine' jewelry when included in quartz, and as a collector's specimen.

Geological facts

Fuchsite is often associated with gold deposits; in some regions, it is known as 'Mariposite' when appearing in dolomitic marble. It is the chromium variety of common muscovite mica.

Field identification & locations

Identify by its distinct emerald-green flaky appearance and its tendency to sparkle (micaceous luster). Commonly found in Precambrian metamorphic terrains, especially in Brazil, India, and Russia.