sedimentary
Jasper (Iron-rich Microcrystalline Quartz)
Silicon Dioxide (SiO2) with Hematite inclusions
Hardness: 6.5–7 on Mohs scale. Color: Brick red to brownish-red (due to iron oxide). Luster: Dull to waxy when unpolished. Crystal Structure: Trigonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.91.
- Hardness
- 6
- Color
- Brick red to brownish-red (due to iron oxide)
- Luster
- Dull to waxy when unpolished
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Physical properties
Hardness: 6.5–7 on Mohs scale. Color: Brick red to brownish-red (due to iron oxide). Luster: Dull to waxy when unpolished. Crystal Structure: Trigonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.91.
Formation & geological history
Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediment. The red color is typically the result of iron oxidation (hematite) during the diagenesis process. Specimens like this often originate from Precambrian or Paleozoic eras.
Uses & applications
Used primarily in lapidary arts for cabochons and beads, as an ornamental stone in construction, and as a popular specimen for crystal healing and amateur rock collecting.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'jasper' is derived from the Greek word 'iaspis', meaning 'spotted stone'. This specific specimen shows 'pitting' common in river-worn or glacially transported quartzites and jaspers.
Field identification & locations
Identify in the field by its opacity (it does not transmit light even on thin edges), its hardness (it should scratch a steel knife), and its smooth, rounded texture when found in riverbeds or glacial tills. Commonly found in the Lake Superior region and western US states.
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