mineral
Tumbled brecciated jasper
Microcrystalline quartz (SiO₂), commonly with iron-oxide and other mineral inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque reddish-brown with gray to black patches, waxy to vitreous luster, and no visible cleavage. The contrasting angular zones suggest brecciation, while the rounded shape is from tumbling and polishing.
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Physical properties
Hardness about 6.5–7 Mohs; opaque reddish-brown with gray to black patches, waxy to vitreous luster, and no visible cleavage. The contrasting angular zones suggest brecciation, while the rounded shape is from tumbling and polishing.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement sedimentary or volcanic material; iron oxides create the red-brown color. Brecciation reflects earlier fracturing and later silica cementation; age depends on its source locality.
Uses & applications
Used as a lapidary stone for cabochons, beads, carvings, and decorative objects. Small tumbled pieces are commonly sold as inexpensive collector or metaphysical specimens.
Geological facts
Its opaque appearance distinguishes jasper from translucent chalcedony or agate. The gray areas may be quartz, chalcedony, or altered host rock rather than a separate gemstone.
Field identification & locations
Identify it by its opaque, fine-grained texture, strong red-brown coloration, and hardness sufficient to scratch glass; a streak test is usually white to pale brown. Common sources include India, Madagascar, Brazil, the western United States, and Australia.
