sedimentary
Jasper
Silicon dioxide (SiO2) with iron impurities
Hardness: 6.5-7 (Mohs); Color: Reddish-brown, dark green, and yellow (mottled); Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Reddish-brown, dark green, and yellow (mottled)
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Reddish-brown, dark green, and yellow (mottled); Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the deposition of silica from water-rich environments or within volcanic ash beds. Over millions of years, heat and pressure solidify the silica into microcrystalline quartz. Variations in mineral impurities (like iron oxides) create the specific coloring.
Uses & applications
Used primarily for semi-precious jewelry (beads and cabochons), ornamental vases, seals, and historical lapidary work. It is a popular stone for tumbling and rock collecting.
Geological facts
The name Jasper comes from the Greek word 'iaspis', meaning 'spotted stone'. It was considered a sacred protection stone in many ancient cultures, including the Egyptians and Native Americans.
Field identification & locations
Identify in the field by its opacity (even when held to light), smooth conchoidal fracture, and high hardness (cannot be scratched by a steel knife). Commonly found in riverbeds and mountainous regions across the United States, India, Brazil, and Russia.
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