sedimentary
River Jasper (Chert/Chalcedony)
Silicon Dioxide (SiO2) with iron oxide impurities
Hardness: 6.5-7 (Mohs scale); Color: Yellow-brown, tan, and black with mottled patterns; Luster: Dull to waxy; Crystal Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.6-2.9
- Hardness
- 6
- Color
- Yellow-brown, tan, and black with mottled patterns
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow-brown, tan, and black with mottled patterns; Luster: Dull to waxy; Crystal Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.6-2.9
Formation & geological history
Formed through the accumulation and silicification of microcrystalline quartz or organic matter in sedimentary environments. Its rounded edges suggest significant weathering and transport in a river or creek bed.
Uses & applications
Used in lapidary work for cabochons and tumbled stones, aquarium decoration, and as a durable material for pathways or landscaping.
Geological facts
Jasper has been used for thousands of years as a gemstone and for making tools due to its hardness and ability to hold a sharp edge when fractured.
Field identification & locations
Identify in the field by its hardness (will scratch glass), smooth waxy feel when wet, and lack of visible grains. Commonly found in riverbeds and gravel pits worldwide.
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