Komatiite is a rare ultramafic volcanic rock characterized by its unique spinifex texture formed by rapid cooling of magnesium-rich lava. It is primarily found in Archean greenstone belts and represents some of the hottest volcanic eruptions in Earth's early history.

Hardness

5-6

Mohs

Luster

Dull

Streak

White

Transparency

Opaque

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Komatiite

Hardness: 5-6
Luster: Dull
Streak: White
Transparency: Opaque

Is this komatiite?

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 komatiite with a known reference. Komatiite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Komatiite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Komatiite typically shows a dull luster.
4
Match the color range
Compare against the expected color range: dark gray, greenish-gray, black.
5
Look at form & habit
Typical habit: massive.

Often confused with

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

How to tell apart: Luster reads dull on Komatiite and vitreous to dull on Peridotite.

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Often found alongside komatiite

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

All properties

Mohs hardness: 5-6
Density: 2.8-3.3 g/cm³
Colors: Dark Gray Greenish-gray Black
Streak: White
Luster: Dull
Transparency: Opaque
Crystal habit: Massive
Cleavage: None
Rarity: Rare
Uses: Geological Research, Collector
Host rock: Archean Volcanic Sequences
Typical price: $10-50 per specimen

Where rockhounds find komatiite

Classic worldwide localities

Barberton Greenstone Belt, South Africa
Abitibi Greenstone Belt, Canada
Yilgarn Craton, Australia
Finland

Field-hunting tip

Look in archean volcanic sequences country — that is the host setting where komatiite typically forms. If you start seeing olivine, pyroxene, chromite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify komatiite?+

Mohs hardness is 5-6. It typically shows a dull luster. The streak is white. Common colors include dark gray, greenish-gray, black.

Where is komatiite found?+

Notable localities include Barberton Greenstone Belt, South Africa; Abitibi Greenstone Belt, Canada; Yilgarn Craton, Australia; Finland.

How much is komatiite worth?+

Typical asking prices fall in the range of $10-50 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like komatiite?+

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

What minerals are found with komatiite?+

Komatiite commonly co-occurs with olivine, pyroxene, chromite, serpentine. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does komatiite form in?+

Komatiite typically forms in archean volcanic sequences. Working float back to the host body is the standard way to chase a fresh occurrence.

What is komatiite used for?+

Komatiite is used in geological research, collector.

Find komatiite on the map

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