sedimentary
Likely river-worn brown jasper or chert pebble
Microcrystalline quartz (SiO₂); exact variety cannot be confirmed from the image
AI-generated identification · may be incorrectOpaque brown, rounded, with pale streaks and a slightly glossy surface. Quartz has Mohs hardness 7, a trigonal crystal structure at the microscopic level, no cleavage, and specific gravity near 2.6; the pebble appears water-worn rather than freshly broken.
Identified More sedimentary →
Explore Likely river-worn brown jasper or chert pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Opaque brown, rounded, with pale streaks and a slightly glossy surface. Quartz has Mohs hardness 7, a trigonal crystal structure at the microscopic level, no cleavage, and specific gravity near 2.6; the pebble appears water-worn rather than freshly broken.
Formation & geological history
Jasper and chert form when silica-rich material precipitates or replaces sediment, commonly in sedimentary settings; the pebble’s rounded shape suggests transport by water. Its geological age cannot be determined visually.
Uses & applications
Commonly used for lapidary carving, tumbled stones, beads, and decorative objects; ordinary pebbles have little commercial value.
Geological facts
Jasper is an opaque, impurity-colored variety of microcrystalline quartz, while chert is the broader rock term; visual inspection alone may not distinguish them.
Field identification & locations
Look for a dense, fine-grained texture, hardness that can scratch glass, and a conchoidal (curved, shell-like) break. Similar pebbles occur in riverbeds and beaches worldwide.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary