Fossil coral is marine coral that has been replaced by silica, preserving the original structure of the organism.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.

Hardness

6.5-7

Mohs

Luster

Waxy

Transparency

Translucent

fossilcommon

Fossil Coral

Hardness: 6.5-7
Luster: Waxy
Transparency: Translucent

Is this fossil coral?

4-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try 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.
2
Name the organism
Decide what left the fossil before worrying about the rock. Organism: Corals (class Anthozoa).
3
Read the luster
Hold the specimen under a strong light. Luster: waxy.
4
Match the color range
Compare against the expected color range: white, tan, brown, red, pink, gray.

Often confused with

Fossil Coral vs. its common look-alikes, and how to tell them apart in the field.

How to tell apart: Luster reads waxy on Fossil Coral and vitreous to waxy on Petrified Wood.

Compare →

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

Mohs hardness: 6.5-7
Density: 2.6-2.7 g/cm³
Colors: White Tan Brown Red Pink Gray
Luster: Waxy
Transparency: Translucent
Rarity: Common
Uses: Lapidary, Collector, Decorative, Jewelry
Host rock: sedimentary strata
Organism: Corals (class Anthozoa)

Where rockhounds find fossil coral

1 mapped spots

Classic worldwide localities

Florida, USA
Indonesia
Utah, USA
Thailand
Georgia, USA

Field-hunting tip

Where it forms: sedimentary strata. If you start seeing quartz, calcite, pyrite in float, you are in the right ground. In the U.S., the densest reported localities are in Florida. Start trip planning there.

Browse 1 U.S. spots for fossil coral →

Common questions

How do you identify fossil coral?+

Mohs hardness is 6.5-7. Organism: Corals (class Anthozoa). Luster: waxy. Common colors include white, tan, brown, red.

Where is fossil coral found?+

Notable localities include Florida, USA; Indonesia; Utah, USA; Thailand; Georgia, USA.

Can I find fossil coral in the United States?+

RockHoundR maps 1 fossil coral rockhounding spots across 1 U.S. states. The top states are Florida.

What rocks look like fossil coral?+

Fossil Coral is most often confused with Chalcedony, Jasper, Petrified Wood. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with fossil coral?+

Fossil Coral commonly co-occurs with Quartz, Calcite, Pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fossil coral form in?+

Where it forms: sedimentary strata. Working float back to the host body is the standard way to chase a fresh occurrence.

What is fossil coral used for?+

Fossil Coral is used in lapidary, collector, decorative, jewelry.

Find fossil coral on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.