Indialite is the high-temperature polymorph of cordierite, structurally analogous to beryl. It is typically found in paralavas and buchites formed by the extreme heating of sediments by igneous intrusions, appearing as small blue to colorless hexagonal crystals.

Hardness

7-7.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareBeryl Group family

Indialite

Hardness: 7-7.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this indialite?

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 indialite with a known reference. Indialite sits at Mohs 7-7.5, 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.
4
Match the color range
Compare against the expected color range: colorless, pale mauve.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: hexagonal, prismatic.

Often confused with

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

Often found alongside indialite

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

All properties

Chemical formula: Mg₂Al₄Si₅O₁₈
Mohs hardness: 7-7.5
Density: 2.512 g/cm³
Colors: ColorlessPale mauve
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Hexagonal, prismatic
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific research
Host rock: Formed by fusion and recrystallization of sedimentary rocks as a result of the burning of underlying coal seams (Bokaro coalfield, India); in cordierite veins in a polymetamorphosed pelitic rock (Unazuki, Japan)

Where rockhounds find indialite

Classic worldwide localities

Pyramid Lake, Washoe Co., Nevada, USA
Bokaro coal seam, southwest of Hazaribagh, Bihar, India
Unazuki area, Toyama Prefecture, Japan
Bellerberg volcano, two km north of Mayen, Eifel district, Germany

Field-hunting tip

Where it forms: Formed by fusion and recrystallization of sedimentary rocks as a result of the burning of underlying coal seams (Bokaro coalfield, India); in cordierite veins in a polymetamorphosed pelitic rock (Unazuki, Japan). If you start seeing enstatite, magnetite, labradorite in float, you are in the right ground. Typical habit: hexagonal, prismatic. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify indialite?+

Mohs hardness is 7-7.5. Luster: vitreous. The streak is white. Common colors include colorless, pale mauve.

Where is indialite found?+

Notable localities include Pyramid Lake, Washoe Co., Nevada, USA; Bokaro coal seam, southwest of Hazaribagh, Bihar, India; Unazuki area, Toyama Prefecture, Japan; Bellerberg volcano, two km north of Mayen, Eifel district, Germany.

What rocks look like indialite?+

Indialite is most often confused with Cordierite, Beryl. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with indialite?+

Indialite commonly co-occurs with Enstatite, Magnetite, Labradorite, Corundum, Cordierite, Andalusite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does indialite form in?+

Where it forms: Formed by fusion and recrystallization of sedimentary rocks as a result of the burning of underlying coal seams (Bokaro coalfield, India); in cordierite veins in a polymetamorphosed pelitic rock (Unazuki, Japan). Working float back to the host body is the standard way to chase a fresh occurrence.

What is indialite used for?+

Indialite is used in collector, scientific research.

Find indialite on the map

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