mineral
Tumbled jasper or chert
Microcrystalline quartz (SiO₂), likely iron-stained jasper/chert
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque mustard-brown color, dull to slightly waxy luster, very fine-grained silica, and no visible cleavage. The rounded shape indicates tumbling or natural water wear.
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 mustard-brown color, dull to slightly waxy luster, very fine-grained silica, and no visible cleavage. The rounded shape indicates tumbling or natural water wear.
Formation & geological history
Forms when silica-rich fluids replace or cement sediment, commonly during diagenesis; iron oxides create the brown coloration. Its exact geological age and locality cannot be determined from the photograph.
Uses & applications
Used for lapidary cabochons, carvings, tumbled stones, and inexpensive jewelry; jasper is also a popular ornamental and collecting material.
Geological facts
Jasper is an opaque variety of chalcedony or microcrystalline quartz, while chert is its broader geological counterpart. Brown coloration commonly reflects hematite or goethite inclusions.
Field identification & locations
Identify by its opaque fine texture, glassy/waxy fracture, lack of cleavage, and ability to scratch ordinary glass; it should not fizz in dilute acid. Common sources include Brazil, Madagascar, India, Australia, and the western United States.
