mineral

Quartz (Iron-stained or Ferruginous Quartz)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Tan to orange-brown due to iron oxide impurities; Luster: Vitreous to greasy; Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Tan to orange-brown due to iron oxide impurities
Luster: Vitreous to greasy

Identified March 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal processes or within igneous pegmatites. This specific water-worn pebble shape suggests it was eroded from its primary source and transported by water over thousands of years.

Uses & applications

Common industrial uses include glass making and silicon manufacturing; iron-stained pebbles are frequently used as decorative landscaping gravel.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. The tan/orange color is often a surface coating of limonite or hematite that has permeated micro-fractures in the gem.

Field identification & locations

Identify by its ability to scratch glass and its lack of cleavage planes. In the field, it will appear transluscent when held to light despite the surface staining. It is found globally in riverbeds and mountainous terrain.

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