Antarcticite is an extremely rare and hygroscopic calcium chloride hexahydrate that typically forms in hyper-saline environments. Because it dissolves rapidly in humid air, specimens must be stored in airtight, sealed containers to prevent them from deliquescing into a liquid. It is most frequently found as delicate, needle-like crystals in extreme desert climates or saline lake beds.
Is this antarcticite?
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 antarcticite with a known reference. Antarcticite 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. Antarcticite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Antarcticite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: acicular or needle-like crystals.
Often confused with
Antarcticite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside antarcticite
Minerals reported to co-occur with antarcticite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCl₂·6H₂O
- Mohs hardness
- 2
- Density
- 1.72 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Acicular or Needle-like Crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Evaporite Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find antarcticite
Classic worldwide localities
- Don Juan Pond, Antarctica
- Bristol Lake, California, USA
- Salton Sea, California, USA
Field-hunting tip
Look in evaporite deposits country — that is the host setting where antarcticite typically forms. If you start seeing halite, gypsum, antarctic ice in float, you are in the right ground. Field specimens usually show a acicular or needle-like crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find antarcticite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
