sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron hydroxides (Goethite/Limonite)
Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow to brownish-yellow; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline (Hexagonal/Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6–2.9
- Hardness
- 6
- Color
- Mustard yellow to brownish-yellow
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow to brownish-yellow; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline (Hexagonal/Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6–2.9
Formation & geological history
Formed through the infiltration of silica-rich fluids into sedimentary or volcanic rocks. The yellow color is derived from iron impurities. It often forms as nodules or in cracks in volcanic deposits and is later weathered and rounded by water action.
Uses & applications
Commonly used in lapidary work for cabochons, beads, and pocket stones. It is also used for decorative carvings and historically for tools due to its conchoidal fracture which creates sharp edges.
Geological facts
Jasper has been used for thousands of years; it was a favorite gemstone in the ancient world, mentioned in the Bible and used by Minoan civilizations for seals. Yellow jasper is specifically associated with solar energy and endurance in folklore.
Field identification & locations
Identify in the field by its opacity (unlike translucent agate), waxy surface when wet, and smooth, rounded water-worn shape. It cannot be scratched by a steel knife. Common in riverbeds and coastal beaches worldwide, particularly in the Pacific Northwest of the USA.
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