Maruyamaite is a very rare potassium-dominant member of the tourmaline group, formally described from specimens in Japan. It typically occurs as small, pale-yellow prisms in highly evolved granitic pegmatites. Collectors value it as a significant species for advanced systematic mineral collections.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareTourmaline Group family

Maruyamaite

Hardness: 7
Luster: Vitreous
Streak: White
Transparency: Translucent

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Is this maruyamaite?

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 maruyamaite with a known reference. Maruyamaite sits at Mohs 7 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Maruyamaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Maruyamaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: pale yellow, yellowish-brown.
5
Look at form & habit
Crystal system: trigonal. Typical habit: prismatic crystals.

Often confused with

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

Often found alongside maruyamaite

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

All properties

Chemical formula: K(MgLi₂Al₆)(Si₆O₁₈)(BO₃)₃(OH)₃F
Mohs hardness: 7
Density: 3.2 g/cm³
Colors: Pale Yellow Yellowish-brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Prismatic Crystals
Cleavage: Indistinct
Rarity: Rare
Uses: Collector
Host rock: Pegmatites
Typical price: $50-500 depending on specimen size and quality

Where rockhounds find maruyamaite

Classic worldwide localities

Kuschiyama, Japan

Field-hunting tip

Look in pegmatites country — that is the host setting where maruyamaite typically forms. If you start seeing quartz, feldspar, mica in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify maruyamaite?+

Mohs hardness is 7. It typically shows a vitreous luster. The streak is white. Common colors include pale yellow, yellowish-brown.

Where is maruyamaite found?+

Notable localities include Kuschiyama, Japan.

How much is maruyamaite worth?+

Typical asking prices fall in the range of $50-500 depending on specimen size and quality. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like maruyamaite?+

Maruyamaite is most often confused with Elbaite, Schorl, Dravite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with maruyamaite?+

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

What kind of rock does maruyamaite form in?+

Maruyamaite typically forms in pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is maruyamaite used for?+

Maruyamaite is used in collector.

Find maruyamaite on the map

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