sedimentary
Fancy Jasper
Silicon Dioxide (SiO2) with mineral inclusions
Hardness: 6.5-7 (Mohs scale), Color: Multicolored (red, black, white, brown), Luster: Vitreous to waxy, Crystal Structure: Microcrystalline (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.9
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Multicolored (red, black, white, brown), Luster: Vitreous to waxy, Crystal Structure: Microcrystalline (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.9
Formation & geological history
Formed through the process of mineralization and deposition of silica-rich fluids in sedimentary environments. Often found as nodules or fillings in fissures, where impurities like iron oxides create the vibrant color patterns.
Uses & applications
Primarily used for lapidary work, jewelry making (cabochons and beads), ornamental carvings, and gathering in rock collections for its aesthetic appeal.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'Fancy Jasper' is a trade term used for specimens with diverse, swirling color patterns. It has been used for seals and amulets since ancient Mesopotamian times.
Field identification & locations
Identify in the field by its high hardness (won't be scratched by a steel knife), smooth waxy feel, and characteristic shell-like (conchoidal) fracture lines. Common in India, Brazil, and the USA.
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