Suessite is a very rare iron silicide mineral found primarily as a component within iron-nickel meteorites. It typically occurs as small inclusions or interstitial grains and is almost exclusively encountered by meteorite researchers and advanced institutional collectors.

Hardness

5-6

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareSilicide family

Suessite

Hardness: 5-6
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this suessite?

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 suessite with a known reference. Suessite 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. Streak: black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: gray white.
5
Look at form & habit
Crystal system: cubic. Typical habit: anhedral grains, microscopic crystals.

Often confused with

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

mineral

Kamacite

Mohs 4

How to tell apart: Suessite is noticeably harder (Mohs 5-6 vs. 4); streak differs, so Suessite leaves black, Kamacite leaves gray.

How to tell apart: Streak differs, so Suessite leaves black, Taenite leaves light gray.

Compare →

Often found alongside suessite

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

All properties

Chemical formula: Fe₃Si
Mohs hardness: 5-6
Density: 7.08 g/cm³
Colors: Gray white
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Anhedral grains, microscopic crystals
Cleavage: None
Rarity: Rare
Uses: Scientific study, Collector
Host rock: In a highly reduced brecciated meteorite (North Haig meteorite); in amygdaloidal basaltic porphyrite (Chatkal Range, Russia)

Where rockhounds find suessite

Classic worldwide localities

Ir-Tash stream basin, Arashan Mountains, Chatkal Range, Uzbekistan

Field-hunting tip

Where it forms: In a highly reduced brecciated meteorite (North Haig meteorite); in amygdaloidal basaltic porphyrite (Chatkal Range, Russia). If you start seeing olivine, pigeonite, kamacite in float, you are in the right ground. Typical habit: anhedral grains, microscopic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify suessite?+

Mohs hardness is 5-6. Luster: metallic. The streak is black. Common colors include gray white.

Where is suessite found?+

Notable localities include Ir-Tash stream basin, Arashan Mountains, Chatkal Range, Uzbekistan.

What rocks look like suessite?+

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

What minerals are found with suessite?+

Suessite commonly co-occurs with Olivine, Pigeonite, Kamacite, Troilite, Carbonaceous material, Khamrabaevite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does suessite form in?+

Where it forms: In a highly reduced brecciated meteorite (North Haig meteorite); in amygdaloidal basaltic porphyrite (Chatkal Range, Russia). Working float back to the host body is the standard way to chase a fresh occurrence.

What is suessite used for?+

Suessite is used in scientific study, collector.

Find suessite on the map

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