mineral
Likely brown rough agate (chalcedony)
Chalcedony, microcrystalline quartz (SiO₂); exact identification is uncertain from the photo
AI-generated identification · may be incorrectBrown, translucent-to-opaque, glassy to waxy luster, with irregular fracture and no obvious cleavage; Mohs hardness about 6.5–7, trigonal quartz structure, specific gravity about 2.6.
Identified More mineral →
Explore Likely brown rough agate (chalcedony) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Brown, translucent-to-opaque, glassy to waxy luster, with irregular fracture and no obvious cleavage; Mohs hardness about 6.5–7, trigonal quartz structure, specific gravity about 2.6.
Formation & geological history
Forms as silica-rich fluid fills cavities and fractures, commonly in volcanic rocks; agate deposits span many geological ages.
Uses & applications
Used for cabochons, beads, carvings, and decorative objects; rough pieces are also collected.
Geological facts
Agate is a banded variety of chalcedony, though bands may be subtle or absent in a small, unpolished fragment.
Field identification & locations
The specimen appears consistent with rough brown chalcedony, but the image does not show diagnostic banding or other features to confirm agate. Common sources include Brazil, Uruguay, India, and the western United States.
More like this
Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Unidentified pink-and-gray mineral or rock specimen
Undetermined; the image is too blurry for reliable identification
mineral