sedimentary
Red Chert / Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale), Color: Red/Brownish-red, Luster: Waxy to dull, Crystal structure: Microcrystalline/Cryptocrystalline (Trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.9
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Red/Brownish-red, Luster: Waxy to dull, Crystal structure: Microcrystalline/Cryptocrystalline (Trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.9
Formation & geological history
Formed through the accumulation of silica-rich microfossils (like radiolarians) or hydrothermal precipitation in marine environments; age varies from Precambrian to Cenozoic.
Uses & applications
Used for making jewelry, lapidary art, aquarium decor, and historically for stone tools due to its sharp edges when fractured.
Geological facts
Jasper has been used as a gemstone since antiquity and is mentioned in many ancient texts. In its red form, the color is primarily due to iron (hematite) inclusions.
Field identification & locations
Look for a microcrystalline texture with a smooth, shells-like (conchoidal) fracture pattern and a hardness that can scratch glass. Common in riverbeds and sedimentary basin outcrops.
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