mineral

Milky Quartz or Moonstone

Silicon Dioxide (SiO2) or Potassium Aluminum Silicate (KAlSi3O8)

Hardness: 6-7 Mohs scale, Color: Tan to light brown with cloudy translucence, Luster: Vitreous to pearly, Crystal structure: Trigonal or Monoclinic, Cleavage: None or imperfect

Identified June 2, 2026More mineral →

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Physical properties

Hardness: 6-7 Mohs scale, Color: Tan to light brown with cloudy translucence, Luster: Vitreous to pearly, Crystal structure: Trigonal or Monoclinic, Cleavage: None or imperfect

Formation & geological history

Quartz forms in igneous, metamorphic, and sedimentary environments; Moonstone specifically forms from sodium-rich and potassium-rich feldspar layers that intergrow causing light scattering (adularescence).

Uses & applications

Used frequently in jewelry as polished cabochons or tumbled stones, and as metaphysical or healing crystals.

Geological facts

This specimen displays tumble-polishing. If it is moonstone, the internal structure reflects light in a phenomenon called adularescence, which was once thought to be captured moonlight.

Field identification & locations

Identify by its cloudy translucence and waxy-to-vitreous feel. Commonly found in riverbeds as pebbles or in pegmatite deposits. Tumbled varieties like this are ubiquitous in crystal shops.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic