Meta-aluminite is a rare secondary sulfate mineral formed by the dehydration of aluminite. It typically appears as dull, white earthy masses or crusts within clay deposits and is primarily sought after by advanced collectors of rare sulfate minerals.
Is this meta-aluminite?
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 meta-aluminite with a known reference. Meta-aluminite 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: somewhat silky.
- 4Match the color rangeCompare against the expected color range: snow white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: aggregates, nodular.
Often confused with
Meta-aluminite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads somewhat silky on Meta-aluminite and dull to earthy on Aluminite.
How to tell apart: Luster reads somewhat silky on Meta-aluminite and vitreous, pearly on cleavage surfaces, dull in aggregates on Gibbsite.
How to tell apart: Luster reads somewhat silky on Meta-aluminite and pearly to dull earthy on Kaolinite.
Often found alongside meta-aluminite
Minerals reported to co-occur with meta-aluminite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂SO₄(OH)₄·5H₂O
- Mohs hardness
- 1-2
- Density
- 2.18 g/cm³
- Colors
- Streak
- White
- Luster
- Somewhat silky
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Aggregates, nodular
- Cleavage
- None observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral formed by reaction of acid sulfate solutions from oxidizing pyrite reacting with clay minerals (Fuemrole mine, Utah, USA)
Where rockhounds find meta-aluminite
Classic worldwide localities
- Fuemrole mine, Temple Mountain, Emery Co., Utah, USA
- Newhaven, Sussex, England
Field-hunting tip
Where it forms: A rare secondary mineral formed by reaction of acid sulfate solutions from oxidizing pyrite reacting with clay minerals (Fuemrole mine, Utah, USA). If you start seeing gypsum, basaluminite in float, you are in the right ground. Typical habit: aggregates, nodular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify meta-aluminite?+
Where is meta-aluminite found?+
What rocks look like meta-aluminite?+
What minerals are found with meta-aluminite?+
What kind of rock does meta-aluminite form in?+
What is meta-aluminite used for?+
Find meta-aluminite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
