mineral
Tumbled yellow jasper or petrified wood fragment
Microcrystalline quartz (chalcedony), SiO₂, possibly iron-oxide-bearing jasper
AI-generated identification · may be incorrectOpaque mustard-yellow, cream, and brown with a waxy-to-dull luster and polished rounded surface; hardness about 6.5–7 Mohs, no visible cleavage, cryptocrystalline structure, and specific gravity near 2.6. The small size and indistinct pattern make exact identification uncertain from the image alone.
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Physical properties
Opaque mustard-yellow, cream, and brown with a waxy-to-dull luster and polished rounded surface; hardness about 6.5–7 Mohs, no visible cleavage, cryptocrystalline structure, and specific gravity near 2.6. The small size and indistinct pattern make exact identification uncertain from the image alone.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement sediments, commonly incorporating iron oxides that produce yellow, orange, and brown colors; formation ages vary widely from Precambrian to recent. If the pattern is cellular or woody under magnification, it may instead be silicified petrified wood.
Uses & applications
Used as inexpensive lapidary material for cabochons, beads, tumbled stones, and small carvings; valued mainly for color and pattern rather than rarity.
Geological facts
Jasper is an opaque variety of chalcedony, unlike agate, which is typically translucent and banded. A glassy scratch test should not be attempted on the specimen; a steel point may be scratched by quartz-rich material.
Field identification & locations
Common in volcanic and sedimentary terrains worldwide, including the western United States, Madagascar, Brazil, and Australia. Look for an opaque body, quartz-like hardness, and iron-stained coloration; a loupe or cut surface can distinguish jasper from petrified wood.
