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, 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.
