sedimentary
Jasper (Mookaite / Brecciated Jasper)
Microcrystalline Quartz (SiO2 with iron oxide inclusions)
Hardness 6.5-7 on Mohs scale; waxy to dull luster when unpolished, vitreous/smooth when polished; opaque; microcrystalline/trigonal structure; reddish-brown, tan, and cream-colored mottled patterns.
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Physical properties
Hardness 6.5-7 on Mohs scale; waxy to dull luster when unpolished, vitreous/smooth when polished; opaque; microcrystalline/trigonal structure; reddish-brown, tan, and cream-colored mottled patterns.
Formation & geological history
Formed through hydrothermal or sedimentary deposition where silica-rich fluids permeate volcanic ash or sedimentary layers, absorbing iron oxides and other minerals that create distinctive banded, brecciated, or variegated color patterns.
Uses & applications
Carved lapidary ornament/decor; used extensively for decorative carvings, cabochons, beads, and gemstone collecting.
Geological facts
Jaspers are opaque varieties of chalcedony that get their rich red, yellow, and brown tones from iron oxide impurities. Carvings into animal shapes like butterflies are popular decorative lapidary arts.
Field identification & locations
Identify by its hardness (scratches glass, cannot be scratched by a steel knife), conchoidal fracture, smooth polished surface, and distinct opaque swirling colors. Commonly mined in Australia, Brazil, South Africa, and the USA.
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