sedimentary
Jasper and Agate
Chalcedony (SiO2 with impurities)
Hardness: 6.5-7 (Mohs), Color: Red, brown, white, and translucent gray, Luster: Vitreous to waxy, Crystal Structure: Microcrystalline (trigonal), Cleavage: None/Conchoidal
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs), Color: Red, brown, white, and translucent gray, Luster: Vitreous to waxy, Crystal Structure: Microcrystalline (trigonal), Cleavage: None/Conchoidal
Formation & geological history
Formed from silica-rich fluids precipitating in the cavities of volcanic or sedimentary rocks. The red color is caused by iron inclusions. Found in abundance in the American Southwest.
Uses & applications
Tumbled for use in jewelry (costume jewelry), lapidary art, and collection.
Geological facts
These specimens are polished 'river rocks' often found in the desert Southwest including New Mexico. Red jasper has been used since antiquity for talismans and seal stones.
Field identification & locations
Commonly found in gravel bars and desert washes. Identify by its opacity (jasper) versus translucency (agate) and its extreme hardness; it will scratch glass.
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