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, 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.
