Shirozulite is a rare manganese-dominant member of the mica group. It is typically found as small, brownish, platy crystals in manganese deposits, often appearing very similar to common biotite mica.

Hardness

2.5-3

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrareMica Group family

Shirozulite

Shirozulite is a rare manganese-dominant member of the mica group. It is typically found as small, brownish, platy crystals in manganese deposits, often appearing very similar to common biotite mica.

Hardness: 2.5-3
Luster: Pearly
Streak: White
Transparency: Translucent

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Is this shirozulite?

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 shirozulite with a known reference. Shirozulite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Shirozulite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Shirozulite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: brown, dark brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals, micaceous aggregates.

Often confused with

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

Often found alongside shirozulite

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

All properties

Chemical formula: KMn₃(Si₃Al)O₁₀(OH)₂
Mohs hardness: 2.5-3
Density: 3.1-3.2 g/cm³
Colors: Brown Dark Brown
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals, Micaceous Aggregates
Cleavage: Perfect Basal
Rarity: Rare
Uses: Collector
Host rock: Manganese-rich Metamorphic Rocks
Typical price: $50-300 per specimen

Where rockhounds find shirozulite

Classic worldwide localities

Shiromaru mine, Japan
Tanokami, Japan

Field-hunting tip

Look in manganese-rich metamorphic rocks country — that is the host setting where shirozulite typically forms. If you start seeing quartz, manganese minerals, feldspar in float, you are in the right ground. Field specimens usually show a platy crystals, micaceous aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify shirozulite?+

Mohs hardness is 2.5-3. It typically shows a pearly luster. The streak is white. Common colors include brown, dark brown.

Where is shirozulite found?+

Notable localities include Shiromaru mine, Japan; Tanokami, Japan.

How much is shirozulite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like shirozulite?+

Shirozulite is most often confused with Biotite, Phlogopite, Annite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with shirozulite?+

Shirozulite commonly co-occurs with Quartz, Manganese minerals, Feldspar. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does shirozulite form in?+

Shirozulite typically forms in manganese-rich metamorphic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is shirozulite used for?+

Shirozulite is used in collector.

Find shirozulite on the map

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