Rock Identifier
Fancy Jasper (Silicon Dioxide (SiO2) with mineral inclusions) — sedimentary
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
Identified More sedimentary

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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.