Indigirite is an extremely rare hydrated magnesium aluminum carbonate mineral typically found as white to pale blue crusts or coatings. It is primarily known from its type locality in the Indigirka River basin of Russia, usually forming in the secondary oxidation zones of sulfide-rich deposits. Collectors prize it for its scarcity and characteristic lamellar crystal structure.

Hardness

Mohs

Luster

Vitreous to silky

Streak

White

Transparency

Semitransparent

mineralrare

Indigirite

Hardness: ~2
Luster: Vitreous to silky
Streak: White
Transparency: Semitransparent

Is this indigirite?

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 indigirite with a known reference. Indigirite sits at Mohs ~2, 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 to silky.
4
Match the color range
Compare against the expected color range: snow white.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: acicular.

Often confused with

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

mineral

Hydromagnesite

Mohs 3.5

How to tell apart: Hydromagnesite is the harder of the two (Mohs 3.5 vs. ~2).

Often found alongside indigirite

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

All properties

Chemical formula: Mg₂Al₂(CO₃)₄(OH)₂·15H₂O
Mohs hardness: ~2
Density: 1.6 g/cm³
Colors: Snow white
Streak: White
Luster: Vitreous to silky
Transparency: Semitransparent
Crystal system: Monoclinic
Crystal habit: Acicular
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: A rare filling in cracks in shale in the oxidized portions of a hydrothermal vein Au–Sb deposit

Where rockhounds find indigirite

Classic worldwide localities

Sarylakh Au–Sb deposit, upper Indigirka River, northeast Sakha, Russia

Field-hunting tip

Where it forms: A rare filling in cracks in shale in the oxidized portions of a hydrothermal vein Au–Sb deposit. If you start seeing gypsum, gibbsite, kaolinite in float, you are in the right ground. Typical habit: acicular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify indigirite?+

Mohs hardness is ~2. Luster: vitreous to silky. The streak is white. Common colors include snow white.

Where is indigirite found?+

Notable localities include Sarylakh Au–Sb deposit, upper Indigirka River, northeast Sakha, Russia.

What rocks look like indigirite?+

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

What minerals are found with indigirite?+

Indigirite commonly co-occurs with Gypsum, Gibbsite, Kaolinite, Hexahydrite, Melanterite, Amorphous Fe oxide. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does indigirite form in?+

Where it forms: A rare filling in cracks in shale in the oxidized portions of a hydrothermal vein Au–Sb deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is indigirite used for?+

Indigirite is used in collector.

Find indigirite on the map

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