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, 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.