mineral

Quartz with Orthoclase Feldspar

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

Hardness: 6-7 (Mohs); Color: White, tan, and reddish-brown; Luster: Vitreous to dull; Crystal structure: Hexagonal (quartz) and Monoclinic (feldspar); Specific gravity: 2.5-2.7

Hardness: 6-7 (Mohs)
Color: White, tan, and reddish-brown
Luster: Vitreous to dull

Identified June 21, 2026More mineral →

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Physical properties

Hardness: 6-7 (Mohs); Color: White, tan, and reddish-brown; Luster: Vitreous to dull; Crystal structure: Hexagonal (quartz) and Monoclinic (feldspar); Specific gravity: 2.5-2.7

Formation & geological history

Formed in granitic pegmatites or hydrothermal veins where magma cools slowly, allowing for the growth of distinct crystals. These specimens can range from Precambrian to Cenozoic in age.

Uses & applications

Mainly collected as geological specimens. Quartz is used in electronics and glass-making, while feldspar is used in ceramics and glass manufacture.

Geological facts

This specimen displays a 'graphic' or interlocking growth pattern common in pegmatites. The reddish-brown tint in the feldspar is often due to trace amounts of iron oxide.

Field identification & locations

Identified by the distinct cleavage planes of the feldspar crystals and the conchoidal fracture of the surrounding milky quartz. Commonly found in mountainous regions with igneous intrusions.

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mineral