Elpasolite is a rare halide mineral primarily found in alkaline pegmatites and cryolite-rich environments. It typically appears as colorless or white masses, and while it is chemically related to other fluorides, its distinct cubic structure helps differentiate it from minerals like cryolite.
Is this elpasolite?
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 elpasolite with a known reference. Elpasolite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: weakly vitreous to slightly greasy.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, granular, or rarely as small cubes.
Often confused with
Elpasolite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads weakly vitreous to slightly greasy on Elpasolite and vitreous to greasy or waxy, pearly on {001} on Cryolite.
How to tell apart: Chiolite is the harder of the two (Mohs 3.5-4 vs. 2.5); luster reads weakly vitreous to slightly greasy on Elpasolite and vitreous, pearly on the basal cleavage on Chiolite.
How to tell apart: Fluorite is the harder of the two (Mohs 4 vs. 2.5); luster reads weakly vitreous to slightly greasy on Elpasolite and vitreous; dull when massive on Fluorite.
Often found alongside elpasolite
Minerals reported to co-occur with elpasolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂NaAlF₆
- Mohs hardness
- 2.5
- Density
- 2.98 g/cm³
- Colors
- Streak
- White
- Luster
- Weakly vitreous to slightly greasy
- Transparency
- Transparent to translucent
- Crystal system
- Cubic
- Crystal habit
- Massive, granular, or rarely as small cubes
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- Replacing fluorine-bearing minerals in a quartz-microcline pegmatite (Pikes Peak, Colorado, USA); on vein quartz in a hydrothermal antimony deposit in silicified limestone (Cetine mine, Italy)
Where rockhounds find elpasolite
Classic worldwide localities
- Cincinnati mine, St. Peters Dome, near Pikes Peak, El Paso Co., Colorado, USA
- Zapot pegmatite, 25 km northeast of Hawthorne, Fitting district, Mineral Co., Nevada, USA
- Morefield pegmatite mine, Amelia, Amelia Co., Virginia, USA
- Cetine mine, 20 km southwest of Siena, Tuscany, Italy
- Ivigtut cryolite deposit, southwestern Greenland
Field-hunting tip
Where it forms: Replacing fluorine-bearing minerals in a quartz-microcline pegmatite (Pikes Peak, Colorado, USA); on vein quartz in a hydrothermal antimony deposit in silicified limestone (Cetine mine, Italy). If you start seeing cryolite, pachnolite, thomsenolite in float, you are in the right ground. Typical habit: massive, granular, or rarely as small cubes. Train your eye for that shape before scanning the outcrop.
Common questions
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Find elpasolite on the map
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