sedimentary
Yellow Jasper (Chert)
Silicon Dioxide (SiO2) with iron inclusions
Hardness: 6.5-7 on Mohs scale. Color: Mustard yellow to golden brown with iron staining. Luster: Waxy to vitreous. Crystal Structure: Hexagonal (microcrystalline). Cleavage: None, exhibits conchoidal fracture.
- Hardness
- 6
- Color
- Mustard yellow to golden brown with iron staining
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Mustard yellow to golden brown with iron staining. Luster: Waxy to vitreous. Crystal Structure: Hexagonal (microcrystalline). Cleavage: None, exhibits conchoidal fracture.
Formation & geological history
Formed from the deposition of silica in groundwater or hydrothermal fluids, often replacing organic materials or filling cavities in volcanic and sedimentary rocks. Common in ancient seafloor deposits and riverbeds.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), and as a decorative landscaping stone. Historically used for making tools due to its sharp conchoidal fracture.
Geological facts
Yellow jasper is a microcrystalline variety of quartz. It often gets its distinct yellow-brown color from the presence of goethite or other iron oxides embedded within the silicate structure.
Field identification & locations
Identify in the field by its waxy texture, inability to be scratched by a steel knife, and smooth, curved (conchoidal) breaks. Typically found in gravel beds, river banks, and desert washes.
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