Hydrodresserite is an extremely rare barium aluminum carbonate mineral primarily known from the alkaline rocks of Mont Saint-Hilaire in Quebec. It typically forms delicate, radiating clusters of acicular needles and is prized by advanced micromount collectors due to its rarity and specific formation environment.
Is this hydrodresserite?
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 hydrodresserite with a known reference. Hydrodresserite sits at Mohs 3-4, 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.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: triclinic. Typical habit: acicular crystals, radiated aggregates.
Often confused with
Hydrodresserite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside hydrodresserite
Minerals reported to co-occur with hydrodresserite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BaAl₂(CO₃)₂(OH)₄·3H₂O
- Mohs hardness
- 3-4
- Density
- 2.80 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Acicular crystals, radiated aggregates
- Cleavage
- Perfect on {010} and {210}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Very rare, in vugs in metamorphosed limestone, near the contact zone of a dawsonite-rich silicocarbonatite sill
Where rockhounds find hydrodresserite
Classic worldwide localities
- Francon quarry, Montreal Island, Montreal, Quebec, Canada
Field-hunting tip
Where it forms: Very rare, in vugs in metamorphosed limestone, near the contact zone of a dawsonite-rich silicocarbonatite sill. If you start seeing dresserite, weloganite, quartz in float, you are in the right ground. Typical habit: acicular crystals, radiated aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hydrodresserite?+
Where is hydrodresserite found?+
What rocks look like hydrodresserite?+
What minerals are found with hydrodresserite?+
What kind of rock does hydrodresserite form in?+
What is hydrodresserite used for?+
Find hydrodresserite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
