mineral

Potassium Feldspar and Quartz

KAlSi3O8 (Potassium Feldspar) and SiO2 (Quartz)

Hardness: 6-7 (Mohs scale), Color: Pink/Salmon (Feldspar) and Milky White/Translucent (Quartz), Luster: Vitreous to pearly, Crystal structure: Monoclinic or Triclinic (Feldspar) and Trigonal (Quartz), Cleavage: Perfect in two directions for Feldspar, none for Quartz.

Identified May 3, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling and crystallization of felsic magma in intrusive igneous environments like granite batholiths, or found as clastic grains in sedimentary rocks.

Uses & applications

Used in the manufacture of glass and ceramics, as abrasives, as decorative stones, and semi-precious gemstones in jewelry.

Geological facts

Feldspars make up about 41% of the Earth's continental crust by weight. Quartz is the second most abundant mineral in Earth's continental crust.

Field identification & locations

Identify by testing hardness (cannot be scratched by a steel knife) and looking for the characteristic salmon-pink color of K-feldspar and the conchoidal fracture of quartz. Commonly found in riverbeds and mountainous terrain.

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

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock

Granite

Granite (Phaneritic intrusive igneous rock)

igneous