sedimentary
Yellow Jasper
Cryptocrystalline Quartz (SiO2) with iron inclusions
Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow to dark brown, Luster: Waxy to vitreous when wet, Crystal Structure: Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.91
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow to dark brown, Luster: Waxy to vitreous when wet, Crystal Structure: Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.91
Formation & geological history
Formed via the deposition of silica from water-saturated solutions in volcanic ash or sedimentary beds. The yellow color is caused by the inclusion of iron hydroxides like goethite or limonite.
Uses & applications
Commonly used in lapidary work for cabochons, beads, and stone carving. It is also used as a decorative landscaping stone and a collector's specimen.
Geological facts
Yellow Jasper was historically used by ancient civilizations as a stone of protection and was often referred to as a 'rain bringer'. It is chemically similar to agate but is opaque rather than translucent.
Field identification & locations
Identify by its smooth texture, opaque yellow coloring, and lack of visible crystalline structure. Look for it in riverbeds or coastal areas where quartz-rich rocks are eroded. Use a steel file to check for hardness; it should not scratch easily.
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