Celestine is a strontium sulfate mineral best known for its stunning, pale sky-blue crystals found in sedimentary vugs and geodes. Collectors typically look for its characteristic orthorhombic tabular habits, often associated with calcitic or dolomitic matrix.
Spotting celestine in the field
Field marks- 1
Pale sky blue, though often colorless or white, in tabular or prismatic crystals
- 2
Heavy for a pale mineral, though slightly less so than barite
- 3
Soft at 3 to 3.5, with good cleavage, and gives a crimson flame test
Celestine (also sold as celestite) is strontium sulfate, the barite twin, and the two are genuinely difficult to separate by eye. The flame test resolves it: strontium burns crimson, barium burns green. It forms in sedimentary rock, especially in limestone and evaporite settings, and geodes lined with pale blue celestine from Madagascar are among the most widely sold mineral specimens in the world. Clay Center in Ohio produced the famous American crystals.
Straight answers
- Is it worth cutting?
- Too soft and too fragile to cut. A display mineral.
- What is it really worth?
- Inexpensive, since Madagascar geodes are abundant. Large well-formed American crystals are collectible.
- Can you legally keep it?
- Ordinary personal-use collecting rules apply. The Ohio localities are private quarries.
Often confused with
Celestine vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside celestine
Minerals reported to co-occur with celestine. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SrSO₄
- Mohs hardness
- 3-3.5
- Density
- 3.95-3.97 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular, Prismatic, Or Pyramidal Crystals, Often in Geodes
- Cleavage
- Perfect in One Direction
- Fluorescence
- None to Faint Blue Under UV
- Rarity
- Common
- Uses
- Collector, Decorative, Industrial Source of Strontium
- Host rock
- Sedimentary Limestones and Evaporite Deposits
Where rockhounds find celestine
3 mapped spotsClassic worldwide localities
- Madagascar
- United States (Ohio)
- Mexico
- Italy
- Poland
Field-hunting tip
Look in sedimentary limestones and evaporite deposits country, the host setting where celestine typically forms. If you start seeing calcite, sulfur, fluorite in float, you are in the right ground. Field specimens usually show a tabular, prismatic, or pyramidal crystals, often in geodes habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Connecticut, Pennsylvania, Wisconsin. Start trip planning there.
More celestine photos
Common questions
How do you identify celestine?+
Where is celestine found?+
Can I find celestine in the United States?+
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Find celestine on the map
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