mineral

Quartz / Feldspar Specimen

SiO2 (Quartz) / KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8 (Feldspar Group)

Hardness: 6-7 on Mohs scale. Color: Off-white, yellowish, cream to milky translucent. Luster: Vitreous to pearly on cleavage faces. Cleavage: Perfect two-direction cleavage at nearly 90 degrees if feldspar-rich; conchoidal fracture if quartz-rich. Specific gravity: 2.56-2.65.

Hardness: 6-7 on Mohs scale
Color: Off-white, yellowish, cream to milky translucent
Luster: Vitreous to pearly on cleavage faces

Identified July 24, 2026More mineral →

Explore Quartz / Feldspar Specimen in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed primarily in igneous pegmatites and granitic intrusions, as well as high-grade metamorphic rocks and hydrothermal veins.

Uses & applications

Feldspar and quartz are heavily used in ceramics, glassmaking, fillers in paint and plastics, and as common decorative or educational specimens for collectors.

Geological facts

Feldspars make up more than 50% of the Earth's crust, while quartz is the second most abundant mineral in the continental crust.

Field identification & locations

Identify in the field by its hardness (scratches glass), off-white color, vitreous-to-pearly luster, and blocky cleavage steps. Commonly found worldwide in gravel deposits, granite outcrops, and pegmatites.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Sandstone with Mineral Veining or Crust

Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)

sedimentary

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock