sedimentary (secondary mineral) within igneous
Jasper in Basalt Matrix
Silicon Dioxide (SiO2) with impurities; Chalcedony
Hardness: 6.5-7 (Mohs scale), Color: Opaque yellow to mustard with orange-red banding, Luster: Vitreous to waxy, Crystal Structure: Microcrystalline (Trigonal), Cleavage: None (Conchoidal fracture)
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Opaque yellow to mustard with orange-red banding, Luster: Vitreous to waxy, Crystal Structure: Microcrystalline (Trigonal), Cleavage: None (Conchoidal fracture)
Formation & geological history
Formed when silica-rich fluids filled cavities or vesicles in volcanic rock (like basalt). Minerals precipitated over time as water evaporated or cooled, often during the Cenozoic era. The impurities (iron oxides) create the yellow and red colors.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons and beads), and as an ornamental display stone. High-quality pieces are favored by rock and mineral collectors.
Geological facts
Jasper is often found in the desert regions of the Western United States. The banding seen in this specimen, often called 'ribbon' or 'picture' jasper patterns, is the result of rhythmic deposition of minerals.
Field identification & locations
Identify in the field by its smooth, waxy fracture surface which contrasts sharply with the rough, porous, dark igneous outer crust (matrix). It cannot be scratched by a steel knife. Common in the Oregon and Idaho high desert regions.
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Other sedimentary (secondary mineral) within igneous specimens
Quartz Geode (with Calcite influence)
Silicon Dioxide (SiO2) with possible Calcium Carbonate (CaCO3)
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Quartz Geode
Silicon dioxide (SiO2)
mineral
Quartz Geode Fragment
Silicon Dioxide (SiO2)
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Blue Calcite
Calcium Carbonate (CaCO3)
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Blue Calcite
Calcium Carbonate (CaCO3)
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Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral