sedimentary
Jasper
Jasper (Silicon Dioxide, SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown, earthy tones; Luster: Dull to greasy; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Reddish-brown, earthy tones
- Luster
- Dull to greasy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown, earthy tones; Luster: Dull to greasy; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments. Over time, the silica crystallizes into microcrystalline quartz, with iron inclusions providing the red color.
Uses & applications
Used primarily in lapidary work for jewelry, ornaments, cabochons, and as a decorative stone in architecture and landscaping.
Geological facts
Jasper is an opaque variety of chalcedony. It has been used for thousands of years, appearing in many ancient cultures for seals, talismans, and jewelry due to its toughness and ability to hold a polish.
Field identification & locations
Identify in the field by its opaque nature (unlike translucent agate), conchoidal fracture patterns, and hardness (cannot be scratched by a steel knife). Commonly found in riverbeds or coastal areas.
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