Coral fossils occur when ancient coral colonies are buried in sediment and replaced by silica-rich fluids over millions of years. Look for distinctive floral or honeycomb patterns on the surface that represent the original skeletal structure of the coral polyps. These specimens are highly prized by lapidaries for their intricate internal details and ability to take a high polish.

Hardness

6.5-7

Mohs

Luster

Waxy

Streak

White

Transparency

Translucent

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Coral Fossil

Also: Agatized coral, Petrified coral

Hardness: 6.5-7
Luster: Waxy
Streak: White
Transparency: Translucent

Is this coral fossil?

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 fossil with a known reference. Coral Fossil sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Coral Fossil leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Coral Fossil typically shows a waxy luster.
4
Match the color range
Compare against the expected color range: white, tan, brown, red, orange, pink, gray.
5
Look at form & habit
Typical habit: massive.

Often confused with

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

Often found alongside coral fossil

Minerals reported to co-occur with coral fossil. 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: 2.5-2.7 g/cm³
Colors: White Tan Brown Red Orange Pink Gray
Streak: White
Luster: Waxy
Transparency: Translucent
Crystal habit: Massive
Cleavage: None
Rarity: Common
Uses: Lapidary, Collector, Decorative
Host rock: Sedimentary
Typical price: $5-50 for small cabochons or specimens, $100+ for large polished displays

Where rockhounds find coral fossil

Classic worldwide localities

Florida, USA
Georgia, USA
Indonesia
Hungary

Field-hunting tip

Look in sedimentary country — that is the host setting where coral fossil typically forms. If you start seeing chalcedony, quartz, calcite 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.

Common questions

How do you identify coral fossil?+

Mohs hardness is 6.5-7. It typically shows a waxy luster. The streak is white. Common colors include white, tan, brown, red.

Where is coral fossil found?+

Notable localities include Florida, USA; Georgia, USA; Indonesia; Hungary.

How much is coral fossil worth?+

Typical asking prices fall in the range of $5-50 for small cabochons or specimens, $100+ for large polished displays. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like coral fossil?+

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

What minerals are found with coral fossil?+

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

What kind of rock does coral fossil form in?+

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

What is coral fossil used for?+

Coral Fossil is used in lapidary, collector, decorative.

Find coral fossil on the map

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