Fossil coral is marine coral that has been replaced by silica, preserving the original structure of the organism. Collectors look for intricate, flower-like patterns in cross-sections, which become highly visible when the material is polished.
Is this fossil 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 fossil coral with a known reference. Fossil Coral sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Fossil Coral leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Fossil Coral typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: white, tan, brown, red, pink, gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive.
Often confused with
Fossil Coral vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside fossil coral
Minerals reported to co-occur with fossil coral. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 6.5-7
- Density
- 2.6-2.7 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative, Jewelry
- Host rock
- Sedimentary Strata
- Typical price
- $5-50 for cabs and specimens, $100+ for large polished displays
Where rockhounds find fossil coral
1 mapped spotsClassic worldwide localities
- Florida, USA
- Indonesia
- Utah, USA
- Thailand
- Georgia, USA
Field-hunting tip
Look in sedimentary strata country — that is the host setting where fossil coral typically forms. If you start seeing quartz, calcite, pyrite 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 Florida — start trip planning there.
Common questions
How do you identify fossil coral?+
Where is fossil coral found?+
Can I find fossil coral in the United States?+
How much is fossil coral worth?+
What rocks look like fossil coral?+
What minerals are found with fossil coral?+
What kind of rock does fossil coral form in?+
What is fossil coral used for?+
Find fossil coral on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
