Strontianite is a strontium carbonate mineral that often forms beautiful, radiating clusters of acicular or bladed crystals. It is frequently found in hydrothermal veins and sedimentary deposits, and it is a primary source for strontium compounds used in pyrotechnics and glass manufacturing.
Is this strontianite?
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 strontianite with a known reference. Strontianite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, resinous on breaks.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, pale yellow, pale green, greenish, gray white, yellowish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: columnar, massive, pseudo hexagonal.
Often confused with
Strontianite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside strontianite
Minerals reported to co-occur with strontianite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SrCO₃
- Mohs hardness
- 3.5
- Density
- 3.76 g/cm³
- Streak
- White
- Luster
- Vitreous, resinous on breaks
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Columnar, massive, pseudo hexagonal
- Cleavage
- On {110}, nearly perfect; on {021}, poor; on {010}, interrupted
- Fluorescence
- White under SW UV; cherry red white under LW UV
- Rarity
- Common
- Uses
- Collector, Ore of strontium
- Host rock
- An uncommon low-temperature hydrothermal mineral formed in veins in limestone, marl, and chalk; in geodes and concretions; rarely occurs in hydrothermal metallic veins; common in carbonatites
Where rockhounds find strontianite
3 mapped spotsClassic worldwide localities
- Strontium Hills, 16 km north of Barstow, San Bernardino Co., California, USA
- Homestake mine, Lead, Lawrence Co., South Dakota, USA
- A number of mines around Rosiclare, as the Minerva #1 mine, Cave-in-Rock, Hardin Co., Illinois, USA
- Winfield quarry, Union Co., Pennsylvania, USA
- Strontian, Argyll, Scotland
- Clausthal and Bad Grund, Harz Mountains, Germany
Field-hunting tip
Where it forms: An uncommon low-temperature hydrothermal mineral formed in veins in limestone, marl, and chalk; in geodes and concretions; rarely occurs in hydrothermal metallic veins; common in carbonatites. If you start seeing barite, calcite, celestine in float, you are in the right ground. Typical habit: columnar, massive, pseudo hexagonal. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Indiana, Illinois. Start trip planning there.
Common questions
How do you identify strontianite?+
Where is strontianite found?+
Can I find strontianite in the United States?+
What rocks look like strontianite?+
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Find strontianite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
