mineral
Polished brecciated jasper
Silica-rich microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions
AI-generated identification · may be incorrectTypically hardness 6.5–7 Mohs, opaque, with mottled gray, cream, brown, and black fragments in a brecciated pattern; waxy to dull luster and no visible cleavage. The rounded shape indicates tumbling or natural water wear.
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Physical properties
Typically hardness 6.5–7 Mohs, opaque, with mottled gray, cream, brown, and black fragments in a brecciated pattern; waxy to dull luster and no visible cleavage. The rounded shape indicates tumbling or natural water wear.
Formation & geological history
Forms when silica-rich fluids cement angular rock fragments, often in volcanic or hydrothermal environments; its exact geological age and locality cannot be determined from the image. Common sources include Brazil, Madagascar, India, Australia, and the western United States.
Uses & applications
Used for cabochons, beads, carvings, polished stones, and lapidary collections; occasionally used as decorative aggregate. Small tumbled pieces generally have modest value.
Geological facts
Jasper is an opaque variety of chalcedony, unlike agate, which is usually translucent and banded. Brecciated varieties preserve evidence of fracturing followed by mineral-rich cementation.
Field identification & locations
Identify it by its opaque silica body, conchoidal fracture, hardness, and irregular angular color patches; it should resist scratching by a steel knife but not quartz. A locality-specific identification requires testing or mineralogical analysis.
