
sedimentary
Fancy Jasper
Silicon Dioxide (SiO2) with mineral inclusions
Hardness: 6.5-7 on Mohs scale; Color: Multi-colored (red, green, yellow, brown); Luster: Vitreous to dull; Crystal structure: Trigonal (Microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
- Hardness
- 6
- Color
- Multi-colored (red, green, yellow, brown)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Multi-colored (red, green, yellow, brown); Luster: Vitreous to dull; Crystal structure: Trigonal (Microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
Formation & geological history
Formed through the deposition of silica-rich fluids in volcanic or sedimentary rocks, where microcrystalline quartz aggregates with mineral impurities like iron oxides and silicates. These are often found as nodules or veins within larger host rocks.
Uses & applications
Primarily used for lapidary work, jewelry (cabs, beads), healing stones, and decorative carvings due to its durability and vibrant color patterns.
Geological facts
Jasper is an opaque variety of chalcedony. The 'Fancy' variety is specifically known for its playful mixture of colors within a single specimen, sometimes referred to as 'Rainbow Jasper'. It has been used since antiquity for seals and amulets.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by a steel knife), smooth waxy feel when wet, and lack of transparency. Common in river beds and sedimentary deposits in India, Africa, and Brazil.
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