mineral

Limonite-stained Quartz

Silicon Dioxide (SiO2) with Iron Oxide/Hydroxide (FeO(OH)·nH2O) staining

Hardness: 7 (Mohs); Color: Milky white body with rust-colored orange-brown surface staining; Luster: Vitreous to dull; Crystal structure: Trigonal (hexagonal system); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65.

Hardness: 7 (Mohs)
Luster: Vitreous to dull

Identified April 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins or as a secondary mineral during the weathering of iron-rich sulfides. Most quartz can date back millions of years, found in varied environments including metamorphic and igneous terrains.

Uses & applications

Quartz is primarily used in electronics for its piezoelectric properties, glassmaking, and abrasives. Iron-stained specimens are mostly collected as garden rocks or by beginner hobbyists.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. The 'rusty' color on this specimen is due to the oxidation of iron minerals, essentially making it 'rock rust'.

Field identification & locations

Identify in the field by its hardness (will scratch glass) and lack of cleavage. Look for the distinctive white/clear base under the brown surface layer. Found globally in almost any outcrop or gravel bed.

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