Calcified coral is a fossilized biological remain where the original calcium carbonate structure has been preserved or replaced by minerals. Collectors look for intricate, star-like patterns or honeycomb structures visible on cut and polished surfaces. It is often found in sedimentary layers that were once ancient marine environments.
Is this calcified 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 calcified coral with a known reference. Calcified Coral sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Calcified Coral leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Calcified Coral typically shows a dull to waxy luster.
- 4Match the color rangeCompare against the expected color range: white, brown, tan, gray, pink, yellow.
- 5Look at form & habitTypical habit: massive.
Often confused with
Calcified Coral vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Chalcedony is the harder of the two (Mohs 6.5-7 vs. 3-4); luster reads dull to waxy on Calcified Coral and waxy on Chalcedony.
How to tell apart: Agate is the harder of the two (Mohs 6.5-7 vs. 3-4); luster reads dull to waxy on Calcified Coral and waxy on Agate.
Often found alongside calcified coral
Minerals reported to co-occur with calcified coral. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 3-4
- Density
- 2.6-2.7 g/cm³
- Streak
- White
- Luster
- Dull to Waxy
- Transparency
- Opaque
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Sedimentary Strata
- Typical price
- $5-50 for small specimens, up to $200 for large polished display pieces
Where rockhounds find calcified coral
3 mapped spotsClassic worldwide localities
- Florida, USA
- Indonesia
- Utah, USA
- Madagascar
- Canada
Field-hunting tip
Look in sedimentary strata country, the host setting where calcified coral typically forms. If you start seeing calcite, quartz, dolomite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Iowa. Start trip planning there.
More calcified coral photos
Common questions
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Find calcified coral on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
