Hydroscarbroite is a rare aluminum carbonate mineral typically found as white, chalky, or botryoidal coatings within clay-rich sedimentary environments. It is most easily identified by its soft, porcelain-like appearance and its association with other aluminum-rich secondary minerals in coastal cliff settings.
Is this hydroscarbroite?
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 hydroscarbroite with a known reference. Hydroscarbroite sits at Mohs 1-2, 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: dull.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: massive, chalky, or botryoidal crusts.
Often confused with
Hydroscarbroite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads dull on Hydroscarbroite and vitreous, pearly on cleavage surfaces, dull in aggregates on Gibbsite.
How to tell apart: Luster reads dull on Hydroscarbroite and pearly to dull earthy on Kaolinite.
Often found alongside hydroscarbroite
Minerals reported to co-occur with hydroscarbroite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₁₄(CO₃)₃(OH)₃₆·n H₂O
- Mohs hardness
- 1-2
- Density
- 2.1-2.2 g/cm³
- Colors
- Streak
- White
- Luster
- Dull
- Transparency
- Semitransparent
- Crystal system
- Triclinic
- Crystal habit
- Massive, chalky, or botryoidal crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In vertical fissures in sandstone, intermixed with scarbroite
Where rockhounds find hydroscarbroite
Classic worldwide localities
- South Bay, near Scarborough, Yorkshire, and at Weston Favell, Northamptonshire, England
Field-hunting tip
Where it forms: In vertical fissures in sandstone, intermixed with scarbroite. If you start seeing scarbroite, gibbsite, kaolinite in float, you are in the right ground. Typical habit: massive, chalky, or botryoidal crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hydroscarbroite?+
Where is hydroscarbroite found?+
What rocks look like hydroscarbroite?+
What minerals are found with hydroscarbroite?+
What kind of rock does hydroscarbroite form in?+
What is hydroscarbroite used for?+
Find hydroscarbroite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
