Plombièrite is a rare calcium silicate hydrate typically found as a result of hydrothermal activity, often in association with hot springs or as a secondary mineral in carbonate rocks. Collectors should look for delicate, white, platy or fibrous aggregates in the cavities of altered limestone.
Is this plombièrite?
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 plombièrite with a known reference. Plombièrite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Plombièrite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Plombièrite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy crystals, radial aggregates, fibrous masses.
Often confused with
Plombièrite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside plombièrite
Minerals reported to co-occur with plombièrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₅Si₆O₁₈H₂·8H₂O
- Mohs hardness
- 2
- Density
- 2.1-2.2 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy Crystals, Radial Aggregates, Fibrous Masses
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Alteration Zones in Limestone
- Typical price
- $20-100 for small micro-mounts
Where rockhounds find plombièrite
Classic worldwide localities
- Plombières-les-Bains, France
- Santa Luce, Italy
- La Valentine, France
Field-hunting tip
Look in hydrothermal alteration zones in limestone country, the host setting where plombièrite typically forms. If you start seeing calcite, apophyllite, zeolites in float, you are in the right ground. Field specimens usually show a platy crystals, radial aggregates, fibrous masses habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify plombièrite?+
Where is plombièrite found?+
How much is plombièrite worth?+
What rocks look like plombièrite?+
What minerals are found with plombièrite?+
What kind of rock does plombièrite form in?+
What is plombièrite used for?+
Find plombièrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
