Silicified coral is a fossilized remain where original coral structures have been replaced by microcrystalline silica. Collectors often look for distinct patterns and pore structures retained from the original coral organism, which can be beautifully preserved through agatization.
Is this silicified coral?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch silicified coral with a known reference. Silicified Coral sits at Mohs 6.5-7, softer than the next harder reference, harder than the previous one.
- 2Name the organismDecide what left the fossil before worrying about the rock. Organism: Corals (class Anthozoa).
- 3Check the preservationPreservation: Silica replaces the original carbonate. That controls the weight, the hardness and how the piece takes a polish.
- 4Read the lusterHold the specimen under a strong light. Luster: waxy.
- 5Match the color rangeCompare against the expected color range: white, gray, brown, red, yellow, pink.
Often confused with
Silicified Coral vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside silicified coral
Minerals reported to co-occur with silicified coral. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 6.5-7
- Density
- 2.6-2.7 g/cm³
- Luster
- Waxy
- Transparency
- Translucent
- Rarity
- Common
- Uses
- Lapidary, Decorative, Collector
- Host rock
- sedimentary limestone
- Organism
- Corals (class Anthozoa)
- Preservation
- Silica replaces the original carbonate
Where rockhounds find silicified coral
11 mapped spotsClassic worldwide localities
- Florida, USA
- Tampa Bay, USA
- Indonesia
- Madagascar
Field-hunting tip
Where it forms: sedimentary limestone. If you start seeing quartz, calcite, goethite in float, you are in the right ground. In the U.S., the densest reported localities are in Florida, Iowa, New York. Start trip planning there.
Common questions
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Find silicified coral on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
