mineral
Tumbled jasper or chert
Microcrystalline quartz (SiO₂), likely iron-stained jasper/chalcedony
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque brown, reddish, cream, and gray coloration with waxy to dull luster and no visible cleavage. Its rounded shape and glossy surface indicate natural water-wear or tumbling; exact identification is limited by the image.
Identified More mineral →
Explore Tumbled jasper or chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 6.5–7 Mohs; opaque brown, reddish, cream, and gray coloration with waxy to dull luster and no visible cleavage. Its rounded shape and glossy surface indicate natural water-wear or tumbling; exact identification is limited by the image.
Formation & geological history
Silica-rich groundwater replaced or cemented sediment, commonly incorporating iron oxides that create the brown-red colors. Such material typically formed in sedimentary or volcanic environments, ranging from Paleozoic to recent deposits.
Uses & applications
Used as lapidary material for cabochons, beads, carvings, and tumbled stones; occasionally used decoratively. Common pieces have modest commercial value.
Geological facts
Jasper is opaque microcrystalline quartz, while chalcedony is generally translucent; both may occur together in brecciated or banded material. Iron staining commonly produces the rusty orange and brown tones visible here.
Field identification & locations
Look for a glass-scratching hardness, waxy surface, irregular mottling, and absence of cleavage; it should not fizz in dilute hydrochloric acid. Common sources include river gravels and volcanic-silica deposits worldwide.
