Meta-alunogen is a rare aluminum sulfate hydrate that typically forms as an alteration product of alunogen. It is found as delicate, fibrous crusts or efflorescences in arid mining districts and fumarolic deposits. Collectors should store these specimens in sealed, climate-controlled containers to prevent dehydration or rapid deterioration.
Is this meta-alunogen?
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-alunogen with a known reference. Meta-alunogen 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: waxy to pearly.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, powdery, or efflorescent crusts.
Often confused with
Meta-alunogen vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads waxy to pearly on Meta-alunogen and vitreous to silky on Alunogen.
How to tell apart: Luster reads waxy to pearly on Meta-alunogen and vitreous on Pickeringite.
How to tell apart: Luster reads waxy to pearly on Meta-alunogen and vitreous on Halotrichite.
Often found alongside meta-alunogen
Minerals reported to co-occur with meta-alunogen. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂(SO₄)₃·14H₂O
- Mohs hardness
- 2
- Density
- 2.85 g/cm³
- Colors
- Streak
- White
- Luster
- Waxy to pearly
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, powdery, or efflorescent crusts
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon mineral formed by dehydration of alunogen; found in sulfate-rich hydrothermal deposits and geothermal fields
Where rockhounds find meta-alunogen
Classic worldwide localities
- Alum mines 3.5 km south of Francisco de Vergara, Antofagasta, Chile
- Ruatapu Cave and within the Te Kopia geothermal field, Taupo Volcanic Zone, New Zealand
Field-hunting tip
Where it forms: An uncommon mineral formed by dehydration of alunogen; found in sulfate-rich hydrothermal deposits and geothermal fields. If you start seeing alunogen, pickeringite, halotrichite in float, you are in the right ground. Typical habit: fibrous, powdery, or efflorescent crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify meta-alunogen?+
Where is meta-alunogen found?+
What rocks look like meta-alunogen?+
What minerals are found with meta-alunogen?+
What kind of rock does meta-alunogen form in?+
What is meta-alunogen used for?+
Find meta-alunogen on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
