Chloromagnesite is a rare, extremely deliquescent mineral formed primarily as a volcanic sublimate around fumaroles. Because it absorbs water rapidly from the atmosphere and dissolves, it must be stored in sealed, airtight containers to prevent it from turning into a liquid brine.
Is this chloromagnesite?
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 chloromagnesite with a known reference. Chloromagnesite sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Chloromagnesite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Chloromagnesite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: trigonal. Typical habit: hexagonal plates.
Often confused with
Chloromagnesite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside chloromagnesite
Minerals reported to co-occur with chloromagnesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgCl₂
- Mohs hardness
- 1
- Density
- 2.33 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Hexagonal Plates
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumaroles
- Typical price
- $50-300 per specimen
Where rockhounds find chloromagnesite
Classic worldwide localities
- Vesuvius, Italy
- Mount Etna, Italy
- Kamchatka, Russia
Field-hunting tip
Look in fumaroles country, the host setting where chloromagnesite typically forms. If you start seeing hematite, tenorite, sylvite in float, you are in the right ground. Field specimens usually show a hexagonal plates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify chloromagnesite?+
Where is chloromagnesite found?+
How much is chloromagnesite worth?+
What rocks look like chloromagnesite?+
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Find chloromagnesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
