
sedimentary
Jasper
Cryptocrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Yellow-brown, tan, ochre, with greyish veining; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.6-2.9.
- Hardness
- 6
- Color
- Yellow-brown, tan, ochre, with greyish veining
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow-brown, tan, ochre, with greyish veining; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.6-2.9.
Formation & geological history
Formed through the accumulation of fine silica from groundwater in sedimentary environments, often replacing volcanic ash or organic matter over millions of years. This piece shows signs of stream-tumbling (rounded edges).
Uses & applications
Popular for lapidary work, decorative cabochons, jewelry, stone carving, and as a collector's specimen. It is also used in tumble-polishing.
Geological facts
Jasper is colored by impurities, most often iron oxides which provide the yellow and brown hues. The thin dark lines in this specimen are secondary mineral 'veins' that filled cracks in the stone as it formed.
Field identification & locations
Identify in the field by its smoothness, lack of visible grain, and hardness (it will scratch glass). Commonly found in riverbeds, glacial tills, and desert pavements globally.
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