mineral
Likely tumbled jasper or agate
Microcrystalline quartz (SiO₂), possibly iron-rich jasper
AI-generated identification · may be incorrectOpaque to weakly translucent, rounded and polished, with reddish-brown, purple, and dark banded coloration; Mohs hardness 6.5–7, vitreous-to-waxy luster, and no visible cleavage. The blurred image prevents confident distinction from similar quartz-rich stones.
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Physical properties
Opaque to weakly translucent, rounded and polished, with reddish-brown, purple, and dark banded coloration; Mohs hardness 6.5–7, vitreous-to-waxy luster, and no visible cleavage. The blurred image prevents confident distinction from similar quartz-rich stones.
Formation & geological history
Silica-rich groundwater replaced or filled cavities in volcanic rock, with iron and other impurities producing the colors and bands; subsequent tumbling created the smooth shape. Formation may range from Paleozoic to Cenozoic depending on locality.
Uses & applications
Used as a decorative stone, cabochon, bead, paperweight, and inexpensive jewelry material; jasper and agate are popular lapidary rough.
Geological facts
Jasper is generally opaque, whereas agate is commonly translucent and distinctly banded; both are varieties of chalcedony, a microcrystalline form of quartz.
Field identification & locations
Check for glassy/waxy luster, conchoidal fracture, hardness sufficient to scratch ordinary glass, and lack of bubbles or uniform artificial color. Common sources include India, Brazil, Madagascar, Mexico, and the western United States.
