Putnisite is a remarkably rare and chemically unique mineral discovered in Western Australia. It typically appears as small, vibrant pink to violet pseudocubic crystals on a white matrix, often found in association with other strontium-bearing minerals.
Is this putnisite?
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 putnisite with a known reference. Putnisite sits at Mohs 1.5-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Putnisite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Putnisite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: pink, violet, purple, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: pseudocubic crystals.
Often confused with
Putnisite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Strontianite is the harder of the two (Mohs 3.5 vs. 1.5-2); luster reads pearly on Putnisite and vitreous on Strontianite.
How to tell apart: Ankerite is the harder of the two (Mohs 3.5-4 vs. 1.5-2); luster reads pearly on Putnisite and vitreous on Ankerite.
Often found alongside putnisite
Minerals reported to co-occur with putnisite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SrCa₄Cr⁸⁺₈(CO₃)₈SO₄(OH)₁₆·25H₂O
- Mohs hardness
- 1.5-2
- Density
- 2.36 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Pseudocubic Crystals
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sedimentary Volcanic Rocks
- Typical price
- $100-500+ per specimen
Where rockhounds find putnisite
Classic worldwide localities
- Polar Bear Peninsula, Western Australia
Field-hunting tip
Look in sedimentary volcanic rocks country, the host setting where putnisite typically forms. If you start seeing quartz, baryte, strontianite in float, you are in the right ground. Field specimens usually show a pseudocubic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find putnisite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
