sedimentary
Yellow Jasper
Cryptocrystalline quartz (SiO2) with iron inclusions
Hardness: 6.5–7 (Mohs scale); Color: Yellow to mustard-brown; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91
- Hardness
- 6
- Color
- Yellow to mustard-brown
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Yellow to mustard-brown; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91
Formation & geological history
Formed through the infiltration of silica in sedimentary or volcanic rock layers, where it crystallizes with high iron oxide content into a dense, opaque microcrystalline quartz. Often found as water-worn pebbles in stream beds or coastal areas.
Uses & applications
Commonly used in lapidary work for cabochons, beads, and tumbled stones. Historically used for ornaments and seals; also used in decorative landscaping and as an ornamental stone in jewelry.
Geological facts
Jasper is known as the 'supreme nurturer' in various cultures and has been used for thousands of years. The yellow color specifically comes from Goethite or other iron hydroxide inclusions within the silica matrix.
Field identification & locations
Identify in the field by its opacity (unlike translucent agate) and its smooth, rounded, waxy texture when tumbled by water. Found globally but common in regions like the Western USA, Madagascar, and Russia. It will not be scratched by a steel knife.
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