mineral

Iron-stained Quartz

Silicon Dioxide (SiO2) with Limonite/Hematite inclusions

Hardness: 7 on Mohs scale; Color: Tan to reddish-brown; Luster: Vitreous to dull; Crystal structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Tan to reddish-brown
Luster: Vitreous to dull

Identified May 31, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Tan to reddish-brown; Luster: Vitreous to dull; Crystal structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Quartz forms in a wide variety of environments, including hydrothermal veins and igneous intrusions. The brownish coloration is due to the secondary oxidation of iron-bearing minerals (rusting) on the surface or within fractures.

Uses & applications

Used primarily as a decorative garden stone, in construction aggregate, or as a beginning collector specimen. High-purity quartz is used in electronics and glass-making.

Geological facts

This specimen displays 'iron staining,' a common geological phenomenon where iron oxides like limonite coat the quartz, giving it an earthy, rusted appearance rather than its usual clear or white state.

Field identification & locations

Identify by its hardness (it will scratch glass) and the presence of rusty, opaque coatings over a translucent crystalline interior. Common in mountainous regions and riverbeds worldwide.

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