sedimentary
Yellow Chert (Yellow Jasper)
Cryptocrystalline Quartz (SiO2) with Goethite/Limonite inclusions
Hardness: 6.5-7 (Mohs); Color: Yellow-brown, mustard, or ochre; Luster: Dull to waxy; Structure: Microcrystalline; Conchoidal fracture; Specific gravity: approx 2.6
- Hardness
- 6
- Color
- Yellow-brown, mustard, or ochre
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Yellow-brown, mustard, or ochre; Luster: Dull to waxy; Structure: Microcrystalline; Conchoidal fracture; Specific gravity: approx 2.6
Formation & geological history
Formed via the accumulation of silica-rich microfossils or chemical precipitation in marine environments; the yellow color is typically due to iron oxide impurities (limonite) within the silica matrix.
Uses & applications
Commonly used in lapidary work for cabochons and tumbled stones; historically used for flintknapping tools due to its sharp edges; also used as landscaping stone.
Geological facts
Yellow jasper is often considered a stone of endurance and protection. Chert and jasper are essentially the same material, with jasper being the opaque, colorful variety of chert.
Field identification & locations
Identified by its waxy texture, yellow-to-brown color, and smooth conchoidal (shell-like) fracture surfaces. Commonly found in riverbeds and glacial till across North America.
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