sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5-7.0 (Mohs scale); Color: Muted yellow to mustard, often with veins or patterns; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
- Hardness
- 6
- Color
- Muted yellow to mustard, often with veins or patterns
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6.5-7.0 (Mohs scale); Color: Muted yellow to mustard, often with veins or patterns; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
Formation & geological history
Formed through the deposition of silica from water or hydrothermal vents, often settling into sediments or volcanic ash. The yellow color is caused by the inclusion of iron hydroxides like goethite.
Uses & applications
Used primarily in lapidary arts for jewelry, tumbled stones, ornamental carvings, and as a decorative stone in mosaics.
Geological facts
Jasper is an opaque variety of chalcedony. It has been used as a gemstone since antiquity and is mentioned in various historical and religious texts as a precious stone for breastplates and amulets.
Field identification & locations
Identify by its opacity (unlike translucent citrine), waxy feel when polished, and lack of visible crystal faces. It is common in riverbeds and coastal areas in regions like India, Russia, Brazil, and the USA.