sedimentary
Chalcedony in Matrix (likely Agatized Coral or Chert)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: tan, grey, white, translucent blue-grey, Luster: waxy to dull, Crystal Structure: Trigonal (microcrystalline), Specific gravity: 2.6-2.64
- Hardness
- 6
Identified More sedimentary →
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: tan, grey, white, translucent blue-grey, Luster: waxy to dull, Crystal Structure: Trigonal (microcrystalline), Specific gravity: 2.6-2.64
Formation & geological history
Formed through the replacement of calcium carbonate or organic material with silica-rich groundwater. Common in sedimentary environments and fossilized reefs, often dating from the Eocene to Miocene epochs.
Uses & applications
Used for lapidary work, jewelry (when polished), aquarium decor, and as collective mineral specimens.
Geological facts
This specimen appears to be a form of silicated sedimentary rock where rhythmic cavities (vugs) are filled or lined with chalcedony. It shares many characteristics with Florida Agatized Coral, which was named the state stone of Florida in 1979.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel knife) and its botryoidal or waxy translucent interiors within a rough, pitted limestone-like exterior. Commonly found in coastal or riverbed sediments in the Southeast USA.
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