Iseite is a rare manganese molybdenum oxide that forms iron-black poorly-formed crystals. Associated minerals include rhodochrosite, powellite and molybdenite. It was first described from Shobu Fe-Mn deposit, near Ise City, Mie Prefecture, Japan.

Hardness

4-5

Mohs

Luster

Submetallic

Streak

Black

Transparency

Opaque

mineralrare

Iseite

Hardness: 4-5
Luster: Submetallic
Streak: Black
Transparency: Opaque

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Is this iseite?

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 iseite with a known reference. Iseite sits at Mohs 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. Iseite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Iseite typically shows a submetallic luster.
4
Match the color range
Compare against the expected color range: iron-black.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: poorly-formed crystals.

Often confused with

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

mineral

Emmonsite

Mohs 5

How to tell apart: Streak differs, so Iseite leaves black, Emmonsite leaves pale yellow; luster reads submetallic on Iseite and vitreous on Emmonsite.

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Often found alongside iseite

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

All properties

Chemical formula: Mn₂Mo₃O₈
Mohs hardness: 4-5
Density: 5.85 g/cm³
Colors: Iron-black
Streak: Black
Luster: Submetallic
Transparency: Opaque
Crystal system: Hexagonal
Crystal habit: Poorly-formed Crystals
Cleavage: Perfect in One Direction
Rarity: Rare
Uses: Collector
Host rock: Oxidized Tellurium-bearing Hydrothermal Deposits

Where rockhounds find iseite

Classic worldwide localities

Shobu Fe-Mn deposit, Mie Prefecture, Japan

Field-hunting tip

Look in oxidized tellurium-bearing hydrothermal deposits country, the host setting where iseite typically forms. If you start seeing emmonsite, tellurite, paratellurite in float, you are in the right ground. Field specimens usually show a poorly-formed crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify iseite?+

Mohs hardness is 4-5. It typically shows a submetallic luster. The streak is black. Common colors include iron-black.

Where is iseite found?+

Notable localities include Shobu Fe-Mn deposit, Mie Prefecture, Japan.

What rocks look like iseite?+

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

What minerals are found with iseite?+

Iseite commonly co-occurs with Emmonsite, Tellurite, Paratellurite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does iseite form in?+

Iseite typically forms in oxidized tellurium-bearing hydrothermal deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is iseite used for?+

Iseite is used in collector.

Find iseite on the map

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