sedimentary
Red Jasper
Jasper (variety of Chert/Chalcedony, formula SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Deep red to reddish-brown due to iron inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Deep red to reddish-brown due to iron inclusions
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Deep red to reddish-brown due to iron inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.58-2.91.
Formation & geological history
Jasper is an aggregate of microcrystalline quartz and fibrous chalcedony. It forms when silica-rich fluids permeate through volcanic ash or sediment during low-temperature metamorphic or sedimentary processes. The red variety typically gains its color from hematite (iron) impurities that were present during formation.
Uses & applications
Extensively used as a gemstone in jewelry (cabochons, beads), decorative ornaments, and as a component in mosaics. Historically used for making tools like scrapers and arrowheads due to its hardness and sharp fracture edges.
Geological facts
Red Jasper was known as the 'rain bringer' in some ancient cultures and was used for carving amulets in ancient Egypt. It is a crypto-crystalline variety of quartz, meaning its crystals are too small to be seen with a standard microscope.
Field identification & locations
Identify in the field by its opaque red color, high hardness (cannot be scratched by a steel knife), and smooth, waxy surface when wet or polished. Commonly found in riverbeds, glacial tills, and desert pavements worldwide.
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