mineral
Polished jasper
Microcrystalline quartz (SiO₂), likely brecciated or orbicular jasper
AI-generated identification · may be incorrectOpaque, mottled cream, tan, brown, and gray material with a waxy-to-dull luster and irregular polished surface. Hardness is about 6.5–7 Mohs; no visible cleavage; quartz-rich microcrystalline structure; specific gravity approximately 2.6.
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Physical properties
Opaque, mottled cream, tan, brown, and gray material with a waxy-to-dull luster and irregular polished surface. Hardness is about 6.5–7 Mohs; no visible cleavage; quartz-rich microcrystalline structure; specific gravity approximately 2.6.
Formation & geological history
Jasper forms when silica-rich groundwater replaces or fills cavities in volcanic or sedimentary material, often incorporating iron oxides and rock fragments that create the pattern. Its exact geological age and locality cannot be determined from the photograph.
Uses & applications
Used as a lapidary stone for tumbled specimens, cabochons, carvings, beads, and ornamental objects; it is not generally used as a major construction material.
Geological facts
The brown coloration commonly reflects hematite or goethite, while gray and cream areas may be chalcedony or altered host rock. Jasper is technically a quartz variety rather than a single mineral species.
Field identification & locations
Identify it by its opaque patterned appearance, glass-free hardness, and inability to scratch with a steel knife easily; a streak test should be white. Common sources include Brazil, Madagascar, India, Indonesia, and the western United States.
