Aluminocoquimbite is a rare sulfate mineral that typically forms in the oxidized zones of pyrite-rich ore deposits. It closely resembles coquimbite but can be distinguished through chemical analysis, often appearing as pale violet or colorless prismatic crystals in dry mining environments.
Is this aluminocoquimbite?
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 aluminocoquimbite with a known reference. Aluminocoquimbite sits at Mohs 2-3, 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: colorless, pale pink.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals, granular aggregates.
Often confused with
Aluminocoquimbite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside aluminocoquimbite
Minerals reported to co-occur with aluminocoquimbite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂Fe₂(SO₄)₆(H₂O)₁₂·9H₂O
- Mohs hardness
- 2-3
- Density
- 2.03 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic crystals, granular aggregates
- Cleavage
- Imperfect, {101}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A precipitate from volcanic vapors in a fumarole (< 100° C)
Where rockhounds find aluminocoquimbite
Classic worldwide localities
- Alum Grotto, Aeolian Islands (Vulcano), Italy
Field-hunting tip
Where it forms: A precipitate from volcanic vapors in a fumarole (< 100° C). If you start seeing alunogen, coquimbite, krausite in float, you are in the right ground. Typical habit: prismatic crystals, granular aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify aluminocoquimbite?+
Where is aluminocoquimbite found?+
What rocks look like aluminocoquimbite?+
What minerals are found with aluminocoquimbite?+
What kind of rock does aluminocoquimbite form in?+
What is aluminocoquimbite used for?+
Find aluminocoquimbite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
