sedimentary
Chert with Epidote and Jasper inclusions
SiO2 (Silicon Dioxide) with Ca2(Al, Fe)3(SiO4)3(OH) inclusions
Hardness: 6.5-7 (Mohs scale); Color: White, green, and reddish-brown; Luster: Waxy to vitreous; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- White, green, and reddish-brown
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: White, green, and reddish-brown; Luster: Waxy to vitreous; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed via the accumulation of silica-rich microfossils or chemical precipitation in marine environments, with inclusion of iron-rich jasper and green epidote through hydrothermal activity or metamorphism.
Uses & applications
Used primarily for lapidary work, decorative cabochons, and as a collector's specimen. Historically used for stone tools due to its fracture pattern.
Geological facts
This specimen appears to be a 'river-worn' cobble, likely from a high-energy environment like a stream bed which has naturally tumbled and smoothed the surface. It shows a complex mix of various silicate minerals.
Field identification & locations
Identify in the field by its waxy luster, smoothness, and the ability to scratch glass. Commonly found in gravel deposits, river beds, and coastal areas in regions with tectonic activity like the Pacific Northwest.
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