mineral

Quartz (Citrine or Iron-Stained variety)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Yellow, honey-orange, to brownish-amber; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Yellow, honey-orange, to brownish-amber
Luster: Vitreous (glassy)

Identified May 24, 2026More mineral →

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Physical properties

Formation & geological history

Commonly formed in hydrothermal veins or as a secondary mineral filling cavities (geodes) in igneous and sedimentary rocks. The yellow coloration is often due to submicroscopic iron impurities or natural irradiation.

Uses & applications

Used widely in jewelry as a semi-precious gemstone, in sandpaper and abrasives, as a source for silicon in technology, and in glass manufacturing.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Natural citrine is rare; many specimens on the commercial market are heat-treated amethyst or smoky quartz.

Field identification & locations

Identify in the field by its ability to scratch glass, its lack of cleavage (it breaks in smooth, curved surfaces), and its glassy luster. It is common in riverbeds and mountainous terrain worldwide.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

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

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral