Horn corals are extinct solitary corals characterized by their distinct horn-shaped, conical skeletons. They are commonly found in Paleozoic marine sedimentary rocks and are often preserved as calcite or silica replacements.
Is this horn 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 horn coral with a known reference. Horn 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. Horn Coral leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Horn Coral typically shows a dull to waxy luster.
- 4Match the color rangeCompare against the expected color range: gray, tan, brown, white.
- 5Look at form & habitTypical habit: horn-shaped, conical, solitary.
Often confused with
Horn Coral vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside horn coral
Minerals reported to co-occur with horn 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
- 2.7 g/cm³
- Streak
- White
- Luster
- Dull to Waxy
- Transparency
- Opaque
- Crystal habit
- Horn-shaped, Conical, Solitary
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Educational, Lapidary
- Host rock
- Limestone, Shale
- Typical price
- $2-20 per specimen
Where rockhounds find horn coral
19 mapped spotsClassic worldwide localities
- USA (Midwest)
- Canada (Ontario)
- United Kingdom
- Germany
- Morocco
U.S. states with horn coral
Each link opens a state-specific list of mapped rockhounding spots that produce horn coral.
Field-hunting tip
Look in limestone, shale country, the host setting where horn coral typically forms. If you start seeing calcite, dolomite, quartz in float, you are in the right ground. Field specimens usually show a horn-shaped, conical, solitary habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Michigan, New York. Start trip planning there.
Common questions
How do you identify horn coral?+
Where is horn coral found?+
Can I find horn coral in the United States?+
How much is horn coral worth?+
What rocks look like horn coral?+
What minerals are found with horn coral?+
What kind of rock does horn coral form in?+
What is horn coral used for?+
Find horn coral on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
