Cryobostryxite is a rare potassium zinc oxide that forms colorless prismatic to acicular crystals. Associated minerals include gypsum, ralstonite and opal. It was first described from the First scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia.

Hardness
2
Mohs
Luster
Vitreous
Streak
White
Transparency
Transparent

Is this cryobostryxite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

  • 1
    Test the hardness
    Try to scratch cryobostryxite with a known reference. Cryobostryxite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
  • 2
    Check the streak
    Drag the specimen across an unglazed porcelain plate. Cryobostryxite leaves a white streak.
  • 3
    Read the luster
    Hold the specimen under a strong light. Cryobostryxite typically shows a vitreous luster.
  • 4
    Match the color range
    Compare against the expected color range: colorless.
  • 5
    Look at form & habit
    Crystal system: monoclinic. Typical habit: prismatic to acicular crystals.

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
KZnCl₃·2H₂O
Mohs hardness
2
Density
2.30 g/cm³
Colors
Streak
White
Luster
Vitreous
Transparency
Transparent
Crystal system
Monoclinic
Crystal habit
Prismatic to Acicular Crystals
Cleavage
None
Rarity
Rare
Uses
Collector
Host rock
Fumarolic Deposits

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 prismatic to acicular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cryobostryxite?+
Mohs hardness is 2. It typically shows a vitreous luster. The streak is white. Common colors include colorless.
Where is cryobostryxite found?+
Notable localities include Russia; Chile; Italy.
What rocks look like cryobostryxite?+
Cryobostryxite is most often confused with Pickeringite, Halotrichite. A quick hardness test and a streak check separate the look-alikes faster than color alone.
What minerals are found with cryobostryxite?+
Cryobostryxite commonly co-occurs with Jarosite, Gypsum. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does cryobostryxite form in?+
Cryobostryxite typically forms in fumarolic deposits. Working float back to the host body is the standard way to chase a fresh occurrence.
What is cryobostryxite used for?+
Cryobostryxite is used in collector.

Find cryobostryxite on the map

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