Coral consists of the skeletal remains of colonial marine organisms primarily composed of calcium carbonate. Collectors often seek out branching or botryoidal structures, which can be polished to a high luster for jewelry. Note that modern coral harvesting is often restricted to protect reef ecosystems, making vintage specimens highly valued.

Hardness

3-4

Mohs

Luster

Dull to Waxy

Streak

White

Transparency

Opaque

fossilcommon

Coral

Hardness: 3-4
Luster: Dull to Waxy
Streak: White
Transparency: Opaque

Is this coral?

5-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 coral with a known reference. Coral sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Coral leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Coral typically shows a dull to waxy luster.
4
Match the color range
Compare against the expected color range: white, pink, red, orange, brown.
5
Look at form & habit
Typical habit: branching, massive, or columnar.

Often confused with

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

mineral

Rhodochrosite

Mohs 3.5-4

How to tell apart: Luster reads dull to waxy on Coral and vitreous on Rhodochrosite.

How to tell apart: Rhodonite is the harder of the two (Mohs 5.5-6.5 vs. 3-4); luster reads dull to waxy on Coral and vitreous on Rhodonite.

Compare →

Often found alongside coral

Minerals reported to co-occur with coral. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CaCO₃
Mohs hardness: 3-4
Density: 2.6-2.7 g/cm³
Colors: White Pink Red Orange Brown
Streak: White
Luster: Dull to Waxy
Transparency: Opaque
Crystal habit: Branching, Massive, Or Columnar
Cleavage: None
Rarity: Common
Uses: Jewelry, Lapidary, Decorative
Host rock: Marine Sedimentary Deposits
Typical price: $10-100 per specimen

Where rockhounds find coral

2 mapped spots

Classic worldwide localities

Mediterranean Sea
Japan
Taiwan
Red Sea
Australia

Field-hunting tip

Look in marine sedimentary deposits country — that is the host setting where coral typically forms. If you start seeing calcite, aragonite in float, you are in the right ground. Field specimens usually show a branching, massive, or columnar habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Florida, Iowa — start trip planning there.

Browse 2 U.S. spots for coral →

Common questions

How do you identify coral?+

Mohs hardness is 3-4. It typically shows a dull to waxy luster. The streak is white. Common colors include white, pink, red, orange.

Where is coral found?+

Notable localities include Mediterranean Sea; Japan; Taiwan; Red Sea; Australia.

Can I find coral in the United States?+

RockHoundR maps 2 coral rockhounding spots across 2 U.S. states — the top states are Florida, Iowa.

How much is coral worth?+

Typical asking prices fall in the range of $10-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like coral?+

Coral is most often confused with Rhodochrosite, Rhodonite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with coral?+

Coral commonly co-occurs with calcite, aragonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does coral form in?+

Coral typically forms in marine sedimentary deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is coral used for?+

Coral is used in jewelry, lapidary, decorative.

Find coral on the map

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