mineral

Botryoidal Chalcedony (likely Chert or Agatized Coral)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Waxy tan, white, and earthy brown. Luster: Waxy to vitreous. Crystal Structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.65.

Hardness: 6
Color: Waxy tan, white, and earthy brown
Luster: Waxy to vitreous

Identified March 20, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through the precipitation of silica from groundwater in cavities of volcanic or sedimentary rocks. The 'bubbly' botryoidal texture occurs when minerals grow around a central nucleus. Often found in limestone beds as nodular inclusions.

Uses & applications

Used in lapidary work for making cabochons or beads, landscaping, and as decorative display specimens for mineral collectors.

Geological facts

The term 'botryoidal' comes from the Greek word 'botrys', meaning a bunch of grapes. This specimen appears to have a thick weathering rind (cortex) typical of flint or chert nodules found in the Southeastern United States.

Field identification & locations

Identify in the field by its waxy texture, heavy weight for its size, and the characteristic rounded 'bubbly' surface. It will often scratch glass but cannot be scratched by a steel knife. Common in regions with ancient limestone karst topography.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral