sedimentary
Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale), Color: Red, brown, and yellow hues, Luster: Vitreous to dull, Structure: Microcrystalline quartz, 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: Red, brown, and yellow hues, Luster: Vitreous to dull, Structure: Microcrystalline quartz, Cleavage: None/Conchoidal fracture, Specific Gravity: 2.58-2.91
Formation & geological history
Formed from silica-rich fluids (typically from volcanic ash or marine sediments) permeating through rock, often filling cavities or forming layers; colored by iron oxides. Geological age varies greatly from Precambrian to Cenozoic.
Uses & applications
Used primarily in lapidary work, jewelry (cabochons), interior decoration, and as a popular collector's river/beach stone.
Geological facts
The name 'Jasper' is derived from the Greek word 'iaspis', meaning spotted stone. It has been used since antiquity for seals and amulets, often mentioned in early literature as a protective stone.
Field identification & locations
Identify by its opacity (unlike translucent agate) and smooth, waxy surface when wet. Commonly found on coastlines, in gravel pits, and riverbeds where volcanic rocks have eroded.
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