sedimentary
Yellow Jasper
Jasper (Silicon Dioxide, SiO2)
Hardness: 6.5-7.0 (Mohs scale); Color: Mustardy yellow with darker spotting/mottling; Luster: Dull or waxy when dry, glass-like when wet; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Mustardy yellow with darker spotting/mottling
- Luster
- Dull or waxy when dry, glass-like when wet
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Physical properties
Hardness: 6.5-7.0 (Mohs scale); Color: Mustardy yellow with darker spotting/mottling; Luster: Dull or waxy when dry, glass-like when wet; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
Formation & geological history
Formed through the deposition of silica from mineral-rich solutions cooling or evaporating within cracks and cavities of other rocks. The yellow color typically comes from goethite or other iron oxyhydrates. It is commonly found in sedimentary environments and ancient volcanic ash deposits.
Uses & applications
Used primarily for lapidary work, jewelry (beads, cabochons), carvings, and as a popular protection stone for collectors. It has also been used historically as a building material in decorative mosaics.
Geological facts
Jasper is an opaque variety of chalcedony. Historically, it was known as a 'nurturing stone' used in ancient civilizations. Yellow Jasper specifically has been used since ancient Egypt as a protective amulet for travelers.
Field identification & locations
Identify it by its opacity (it does not transmit light even at the edges), its hardness (will scratch glass), and its smooth water-worn texture if found near riverbeds. It is commonly found in the Pacific Northwest, Brazil, and Madagascar.
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