Cryobostryxite is a rare ammonium iron sulfate mineral typically found as delicate, curly fiber-like aggregates in volcanic fumarole environments. It is highly unstable in normal atmospheric conditions, often dehydrating or dissolving if exposed to humidity, making it a challenging and rare acquisition for serious mineral collectors.
Is this cryobostryxite?
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 cryobostryxite with a known reference. Cryobostryxite 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. Cryobostryxite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Cryobostryxite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous to acicular aggregates.
Often confused with
Cryobostryxite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside cryobostryxite
Minerals reported to co-occur with cryobostryxite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NH₄Fe(SO₄)₂·4H₂O
- Mohs hardness
- 2
- Density
- 1.74 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous to Acicular Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Deposits
- Typical price
- expensive due to rarity and instability
Where rockhounds find cryobostryxite
Classic worldwide localities
- Russia
- Chile
- Italy
Field-hunting tip
Look in fumarolic deposits country — that is the host setting where cryobostryxite typically forms. If you start seeing jarosite, gypsum in float, you are in the right ground. Field specimens usually show a fibrous to acicular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cryobostryxite?+
Where is cryobostryxite found?+
How much is cryobostryxite worth?+
What rocks look like cryobostryxite?+
What minerals are found with cryobostryxite?+
What kind of rock does cryobostryxite form in?+
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Find cryobostryxite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
