mineral
Ferruginous Quartz
Silicon Dioxide (SiO2) with Hematite/Limonite inclusions
Hardness: 7 (Mohs scale), Color: White to reddish-brown, Luster: Vitreous to waxy, Crystal Structure: Trigonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: White to reddish-brown, Luster: Vitreous to waxy, Crystal Structure: Trigonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed in hydrothermal veins or as a secondary mineral in sedimentary environments. The reddish tint comes from iron oxide staining during or after the quartz crystallization.
Uses & applications
Used primarily in lapidary work, jewelry making, and as a decorative collector specimen.
Geological facts
Also known as Eisenkiesel, this variety of quartz contains enough iron oxide to color the mineral opaque or semi-translucent red, orange, or brown. It is a common 'river rock' find in regions with iron-rich soil.
Field identification & locations
Identify by its hardness (scratches glass), waxy luster when water-worn, and the characteristic rusty-red staining that cannot be washed off. Commonly found in gravel pits, river beds, and mountainous regions.
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