Kamiokite is a rare iron molybdenum oxide typically found in skarn deposits. It is best identified by its opaque, black metallic luster and its specific paragenesis with molybdenum-bearing minerals in metamorphosed ore bodies.

Hardness

3-4.5

Mohs

Luster

Metallic to submetallic

Streak

Black

Transparency

Opaque

mineralrare

Kamiokite

Hardness: 3-4.5
Luster: Metallic to submetallic
Streak: Black
Transparency: Opaque

Is this kamiokite?

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 kamiokite with a known reference. Kamiokite sits at Mohs 3-4.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic to submetallic.
4
Match the color range
Compare against the expected color range: iron black.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: hexagonal, tabular.

Often confused with

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

How to tell apart: Streak differs, so Kamiokite leaves black, Hematite leaves cherry-red or reddish brown.

How to tell apart: Magnetite is the harder of the two (Mohs 5.5-6.5 vs. 3-4.5).

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Often found alongside kamiokite

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

All properties

Chemical formula: Fe₂Mo₃O₈
Mohs hardness: 3-4.5
Density: 5.96 g/cm³
Colors: Iron black
Streak: Black
Luster: Metallic to submetallic
Transparency: Opaque
Crystal system: Hexagonal
Crystal habit: Hexagonal, tabular
Cleavage: {0001}, perfect
Rarity: Rare
Uses: Collector, Scientific research
Host rock: In quartz-molybdenite stockwork veins associated with granite porphyry dikes (Japan); in fissure veins filled during low-grade regional metamorphism of basalt (Michigan, USA)

Where rockhounds find kamiokite

Classic worldwide localities

Mohawk and Ahmeek mines, Keweenaw Co., Michigan, USA
Kamioka Ag–Pb–Zn mine, Gifu Prefecture, Japan
Carajas deposit, locality not otherwise specified, Brazil

Field-hunting tip

Where it forms: In quartz-molybdenite stockwork veins associated with granite porphyry dikes (Japan); in fissure veins filled during low-grade regional metamorphism of basalt (Michigan, USA). If you start seeing molybdenite, potassic feldspar, fluorite in float, you are in the right ground. Typical habit: hexagonal, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify kamiokite?+

Mohs hardness is 3-4.5. Luster: metallic to submetallic. The streak is black. Common colors include iron black.

Where is kamiokite found?+

Notable localities include Mohawk and Ahmeek mines, Keweenaw Co., Michigan, USA; Kamioka Ag–Pb–Zn mine, Gifu Prefecture, Japan; Carajas deposit, locality not otherwise specified, Brazil.

What rocks look like kamiokite?+

Kamiokite is most often confused with Ilmenite, Hematite, Magnetite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with kamiokite?+

Kamiokite commonly co-occurs with Molybdenite, Potassic feldspar, Fluorite, Ilmenite, Scheelite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does kamiokite form in?+

Where it forms: In quartz-molybdenite stockwork veins associated with granite porphyry dikes (Japan); in fissure veins filled during low-grade regional metamorphism of basalt (Michigan, USA). Working float back to the host body is the standard way to chase a fresh occurrence.

What is kamiokite used for?+

Kamiokite is used in collector, scientific research.

Find kamiokite on the map

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