Chiolite is a rare sodium aluminum fluoride mineral that is structurally related to cryolite. It typically occurs as white or colorless massive aggregates within unique pegmatite environments, most famously associated with the cryolite deposits in Ivigtut, Greenland.

Hardness

3.5-4

Mohs

Luster

Vitreous, pearly on the basal cleavage

Streak

White

Transparency

Transparent to translucent

mineralrare

Chiolite

Hardness: 3.5-4
Luster: Vitreous, pearly on the basal cleavage
Streak: White
Transparency: Transparent to translucent

Is this chiolite?

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 chiolite with a known reference. Chiolite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous, pearly on the basal cleavage.
4
Match the color range
Compare against the expected color range: colorless, snow white.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: crystalline.

Often confused with

Chiolite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Cryolite

Mohs 2.5

How to tell apart: Chiolite is noticeably harder (Mohs 3.5-4 vs. 2.5).

Often found alongside chiolite

Minerals reported to co-occur with chiolite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Na₅Al₃F₁₄
Mohs hardness: 3.5-4
Density: 2.994-3.005 g/cm³
Colors: Colorless Snow white
Streak: White
Luster: Vitreous, pearly on the basal cleavage
Transparency: Transparent to translucent
Crystal system: Tetragonal
Crystal habit: Crystalline
Cleavage: {001}, perfect; {011}, distinct
Rarity: Rare
Uses: Collector, Geological study
Host rock: In some granite pegmatites

Where rockhounds find chiolite

Classic worldwide localities

Morefield pegmatite mine, Amelia, Amelia Co., Virginia, USA
Miass, Ilmen Mountains, Southern Ural Mountains, Russia
Ivigtut cryolite deposit, southwestern Greenland

Field-hunting tip

Where it forms: In some granite pegmatites. If you start seeing topaz, phenakite, fluorite in float, you are in the right ground. Typical habit: crystalline. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify chiolite?+

Mohs hardness is 3.5-4. Luster: vitreous, pearly on the basal cleavage. The streak is white. Common colors include colorless, snow white.

Where is chiolite found?+

Notable localities include Morefield pegmatite mine, Amelia, Amelia Co., Virginia, USA; Miass, Ilmen Mountains, Southern Ural Mountains, Russia; Ivigtut cryolite deposit, southwestern Greenland.

What rocks look like chiolite?+

Chiolite is most often confused with Cryolite, Prosopite, Fluorite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with chiolite?+

Chiolite commonly co-occurs with Topaz, Phenakite, Fluorite, Cryolithionite, Thomsenolite, Cryolite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does chiolite form in?+

Where it forms: In some granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is chiolite used for?+

Chiolite is used in collector, geological study.

Find chiolite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.