Horomanite is a rare iron nickel sulfide that forms grains. It is a filling space between silicate minerals in lherzolites of a peridotite massif. It was first described from Horoman peridotite massif, Samani-cho, Samani-gun, Hokkaido, Japan.

Hardness

Mohs

Luster

Metallic

Transparency

Opaque

mineralrare

Horomanite

Hardness: 3
Luster: Metallic
Transparency: Opaque

No image

Is this horomanite?

4-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 horomanite with a known reference. Horomanite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
2
Read the luster
Hold the specimen under a strong light. Luster: metallic.
3
Match the color range
Compare against the expected color range: brown, yellowish-brown.
4
Look at form & habit
Crystal system: tetragonal. Typical habit: grains.

Often confused with

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

mineral

Kalsilite

Mohs 6

How to tell apart: Kalsilite is the harder of the two (Mohs 6 vs. 3); luster reads metallic on Horomanite and vitreous to greasy on Kalsilite.

Compare →

Often found alongside horomanite

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

All properties

Chemical formula: Fe₆Ni₃S₈
Mohs hardness: 3
Density: 6.44 g/cm³
Colors: Brown Yellowish-brown
Luster: Metallic
Transparency: Opaque
Crystal system: Tetragonal
Crystal habit: Grains
Cleavage: Pronounced
Rarity: Rare
Uses: Collector
Host rock: Filling space between silicate minerals in lherzolites of a peridotite massif

Where rockhounds find horomanite

Classic worldwide localities

Horoman peridotite massif, Samani-cho, Samani-gun, Hokkaido, Japan

Field-hunting tip

Where it forms: Filling space between silicate minerals in lherzolites of a peridotite massif. If you start seeing bornite, talnakhite, copper in float, you are in the right ground. Typical habit: grains. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify horomanite?+

Mohs hardness is 3. Luster: metallic. Common colors include brown, yellowish-brown.

Where is horomanite found?+

Notable localities include Horoman peridotite massif, Samani-cho, Samani-gun, Hokkaido, Japan.

Is horomanite safe to handle?+

Horomanite contains nickel. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like horomanite?+

Horomanite is most often confused with Kalsilite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with horomanite?+

Horomanite commonly co-occurs with Bornite, Talnakhite, Copper, Troilite, Heazlewoodite, Pentlandite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does horomanite form in?+

Where it forms: Filling space between silicate minerals in lherzolites of a peridotite massif. Working float back to the host body is the standard way to chase a fresh occurrence.

What is horomanite used for?+

Horomanite is used in collector.

Find horomanite on the map

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