sedimentary
Jasper / Ferruginous Chert
Microcrystalline Quartz with Hematite inclusions (SiO2 + Fe2O3)
AI-generated identification · may be incorrectHardness 6.5-7 on the Mohs scale, reddish-orange to brownish-red color, dull to waxy luster, conchoidal fracture, and no cleavage.
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Physical properties
Hardness 6.5-7 on the Mohs scale, reddish-orange to brownish-red color, dull to waxy luster, conchoidal fracture, and no cleavage.
Formation & geological history
Formed via chemical precipitation of silica from volcanic or groundwater fluids enriched with iron oxides within sedimentary or metamorphic sequences.
Uses & applications
Commonly used as a lapidary gemstone, for ornamental carvings, polished cabochons, and historic stone tool making.
Geological facts
Iron oxide (hematite) is responsible for its vibrant red-orange color; in the Kalahari-margin region of western Zambia/eastern Angola, silcretes and jaspers frequently occur in ferricretes and ancient river gravels.
Field identification & locations
Identified in the field by its high hardness (scratches glass/steel), smooth to sub-conchoidal fracture, opaque body, and persistent red-orange iron staining.
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