mineral

Greyscale Moonstone / Silver Sheen Moonstone

Potassium Aluminum Silicate (KAlSi3O8)

Hardness: 6-6.5 (Mohs scale); Color: Dark grey, charcoal, or brown with silvery adularescence; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Specific gravity: 2.56-2.59

Hardness: 6-6
Color: Dark grey, charcoal, or brown with silvery adularescence
Luster: Vitreous to pearly

Identified April 4, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (Mohs scale); Color: Dark grey, charcoal, or brown with silvery adularescence; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Specific gravity: 2.56-2.59

Formation & geological history

Formed from cooling magma in igneous intrusions (pegmatites). It results from the intergrowth of orthoclase and albite. As they cool, the two minerals separate into stacked layers, causing light to scatter (adularescence).

Uses & applications

Primarily used in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal collectors.

Geological facts

Grey moonstone is often referred to as 'New Moonstone.' The silvery glow seen on the surface is a light-scattering phenomenon known as adularescence, which occurs within the layered internal structure of the feldspar.

Field identification & locations

Identify by its characteristic 'glow' or sheen that moves beneath the surface as the stone is turned. It is commonly found in India, Sri Lanka, Madagascar, and Myanmar. Field identification relies on hardness and the specific pearly sheen.

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