Tubulite is a descriptive term for cylindrical or tubular fossil casts, often formed by the infilling of burrows or plant stems within carbonate sediment. These structures are frequently composed of calcite or dolomite and are commonly found weathered out of limestone or dolomite strata in the American Midwest.
Is this tubulite?
3-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 tubulite with a known reference. Tubulite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: metallic.
- 3Match the color rangeCompare against the expected color range: black.
Often confused with
Tubulite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside tubulite
Minerals reported to co-occur with tubulite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 3-4
- Density
- 2.6-2.7 g/cm³
- Colors
- Luster
- Metallic
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Collector, Decorative
- Host rock
- sedimentary limestone or dolomite
Where rockhounds find tubulite
Classic worldwide localities
- Illinois, USA
- Iowa, USA
- Wisconsin, USA
Field-hunting tip
Where it forms: sedimentary limestone or dolomite. If you start seeing calcite, dolomite, quartz in float, you are in the right ground.
Common questions
How do you identify tubulite?+
Where is tubulite found?+
What rocks look like tubulite?+
What minerals are found with tubulite?+
What kind of rock does tubulite form in?+
What is tubulite used for?+
Find tubulite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
