A crinoid stem is a fossilized segment of a marine echinoderm, usually found as a stackable, wheel-like disc in limestone. It is identified by its central pentagonal or circular hole and is a staple find for amateur paleontologists in Paleozoic marine strata.

Hardness

3-4

Mohs

Luster

Dull

Streak

White

Transparency

Opaque

fossilcommon

Crinoid Stem

Also: Indian beads, Stone beads, Crinoid ossicles

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

Is this crinoid stem?

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 crinoid stem with a known reference. Crinoid Stem 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. Crinoid Stem leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Crinoid Stem typically shows a dull luster.
4
Match the color range
Compare against the expected color range: gray, white, tan, brown.
5
Look at form & habit
Typical habit: cylindrical segments.

Often found alongside crinoid stem

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

Calcite
mineral · Mohs 3

All properties

Chemical formula: CaCO₃
Mohs hardness: 3-4
Density: 2.6-2.7 g/cm³
Colors: Gray White Tan Brown
Streak: White
Luster: Dull
Transparency: Opaque
Crystal habit: Cylindrical Segments
Cleavage: None
Rarity: Common
Uses: Collector, Decorative, Educational
Host rock: Limestone

Where rockhounds find crinoid stem

3 mapped spots

Classic worldwide localities

Indiana, USA
Ohio, USA
United Kingdom
Germany
Missouri, USA

Field-hunting tip

Look in limestone country, the host setting where crinoid stem typically forms. If you start seeing calcite, brachiopods, bryozoans in float, you are in the right ground. Field specimens usually show a cylindrical segments habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Texas, Michigan. Start trip planning there.

Browse 3 U.S. spots for crinoid stem →

Common questions

How do you identify crinoid stem?+

Mohs hardness is 3-4. It typically shows a dull luster. The streak is white. Common colors include gray, white, tan, brown.

Where is crinoid stem found?+

Notable localities include Indiana, USA; Ohio, USA; United Kingdom; Germany; Missouri, USA.

Can I find crinoid stem in the United States?+

RockHoundR maps 3 crinoid stem rockhounding spots across 2 U.S. states. The top states are Texas, Michigan.

What minerals are found with crinoid stem?+

Crinoid Stem commonly co-occurs with Calcite, Brachiopods, Bryozoans. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does crinoid stem form in?+

Crinoid Stem typically forms in limestone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is crinoid stem used for?+

Crinoid Stem is used in collector, decorative, educational.

Find crinoid stem on the map

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