A celestite concretion forms as a rounded nodule or geodic body within a sedimentary sequence, often with a hollow center lined with delicate, pale blue prismatic crystals. Look for it in sedimentary limestone layers, where the exterior appears as a dull, unremarkable rock hiding a cavity of radiant blue mineral blades.
Is this celestite concretion?
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 celestite concretion with a known reference. Celestite Concretion sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Celestite Concretion leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Celestite Concretion typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, white, colorless, pale yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals within spherical or irregular sedimentary concretions.
Often confused with
Celestite Concretion vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside celestite concretion
Minerals reported to co-occur with celestite concretion. 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
- 3.9-4.0 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals Within Spherical or Irregular Sedimentary Concretions
- Cleavage
- Perfect Basal
- Rarity
- Common
- Uses
- Collector, Decorative
- Host rock
- Sedimentary Limestone or Shale
Where rockhounds find celestite concretion
1 mapped spotsClassic worldwide localities
- Lake Erie (Ohio, USA)
- Madagascar
- Poland
- Tunisia
Field-hunting tip
Look in sedimentary limestone or shale country, the host setting where celestite concretion typically forms. If you start seeing calcite, dolomite, gypsum in float, you are in the right ground. Field specimens usually show a tabular crystals within spherical or irregular sedimentary concretions habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in California. Start trip planning there.
More celestite concretion photos
Common questions
How do you identify celestite concretion?+
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Can I find celestite concretion in the United States?+
What rocks look like celestite concretion?+
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Find celestite concretion on the map
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