mineral
Ferruginous Quartz
Silicon Dioxide (SiO2) with Iron Oxide (Hematite/Limonite) inclusions
Hardness: 7 on Mohs scale; Color: Reddish-orange, peach, or rusty brown; Luster: Vitreous to greasy; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Reddish-orange, peach, or rusty brown
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-orange, peach, or rusty brown; Luster: Vitreous to greasy; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65
Formation & geological history
Formed through hydrothermal processes or secondary staining of quartz crystals by iron-rich groundwater. Often found in sedimentary deposits or as weathered vein quartz, dating from any geological period where silica and iron were present.
Uses & applications
Primary use is in aesthetic jewelry (beads, cabochons), lapidary art, and rock collecting. Historically used for carving and as a decorative stone.
Geological facts
Also known as 'Eisenkiesel' in German (meaning iron-pebble). The red color is caused by microscopic hematite or goethite crystals trapped inside the quartz matrix or coating the exterior surfaces.
Field identification & locations
Identify in the field by its superior hardness (cannot be scratched by a steel knife) and the characteristic sparkle of quartz underlying the rusty hue. Found globally in iron-rich soils, riverbeds, and quartz veins.
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