Sedimentary/Mineral
Jasper
Chalcedony (SiO2)
Hardness: 6.5-7, Color: Opaque dark matrix with reddish-brown to tan brecciated veins or inclusions, Luster: Vitreous to dull, Crystal structure: Microcrystalline quartz, Cleavage: None
- Hardness
- 6
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Physical properties
Hardness: 6.5-7, Color: Opaque dark matrix with reddish-brown to tan brecciated veins or inclusions, Luster: Vitreous to dull, Crystal structure: Microcrystalline quartz, Cleavage: None
Formation & geological history
Forms in vein fillings or as nodules in sedimentary rocks or volcanic rocks where silica-rich waters percolate. Brecciated patterns form when the rock is fractured and later cemented by silica.
Uses & applications
Commonly used in jewelry making (cabochons, pendants, beads) and lapidary arts.
Geological facts
Jasper comes in many local varieties named for their patterns or locations. The specimen shown appears to be a brecciated jasper or perhaps a type of coquina jasper (Script stone) depending on the specific inclusions.
Field identification & locations
Identify by its opacity, hardness (scratches glass), and characteristic patterns. Widely found globally.
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