sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: reddish-brown, tan, and gray waxy luster; Conchoidal fracture; Opaque to translucent; Trigonal crystal system (microscopic).
- Hardness
- 6
- Color
- reddish-brown, tan, and gray waxy luster
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Physical properties
Hardness: 6.5-7 Mohs; Color: reddish-brown, tan, and gray waxy luster; Conchoidal fracture; Opaque to translucent; Trigonal crystal system (microscopic).
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. The reddish hues suggest iron oxide mineralization.
Uses & applications
Historically used for stone tools and arrowheads; currently used in jewelry (as jasper), landscaping, and as an industrial abrasive.
Geological facts
Chert is so hard it can strike sparks from steel. Varieties rich in iron oxide are specifically known as jasper, often used as semi-precious gemstones.
Field identification & locations
Look for a smooth, waxy surface and conchoidal (shell-like) fractures. Common in riverbeds and limestone outcrops. Often found as rounded nodules or pebbles.
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Clastic Sedimentary Rock Grain (SiO2 dominated)
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Chert Breccia
Brecciated Chert (Microcrystalline Silica)
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