Taneyamalite is a rare manganese-bearing silicate mineral belonging to the ardennite group. It typically occurs as small, delicate, radiating fibrous aggregates within manganese-rich metamorphic environments and is highly sought after by systematic mineral collectors.

Hardness

5-6

Mohs

Luster

Vitreous

Streak

Light yellow, brown

Transparency

Translucent

mineralrareArdennite Group family

Taneyamalite

Hardness: 5-6
Luster: Vitreous
Streak: Light yellow, brown
Transparency: Translucent

Is this taneyamalite?

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 taneyamalite with a known reference. Taneyamalite sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: light yellow, brown.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: greenish yellow, grayish yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: acicular, flakes.

Often found alongside taneyamalite

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

All properties

Chemical formula: (Na,Ca)Mn₁₂(Si,Al)₁₂(O,OH)₄₄
Mohs hardness: 5-6
Density: 3.30 g/cm³
Colors: Greenish yellow Grayish yellow
Streak: Light yellow, brown
Luster: Vitreous
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Acicular, flakes
Cleavage: Perfect to good on (010), fair on (100)
Rarity: Rare
Uses: Collector
Host rock: In cracks in ferruginous chert, mafic rocks, and limestone subjected to blueschist facies metamorphism (Taneyama mine, Japan)

Where rockhounds find taneyamalite

Classic worldwide localities

Ward Creek, near Cazadero, and along the Russian River, Sonoma Co., and Pacheco Pass, Santa Clara Co., California, USA
Taneyama mine, Kumamoto Prefecture, and the Iwaizawa mine, near Agano, Saitama Prefecture, Japan
Brezovia, Yugoslavia

Field-hunting tip

Where it forms: In cracks in ferruginous chert, mafic rocks, and limestone subjected to blueschist facies metamorphism (Taneyama mine, Japan). If you start seeing quartz, hematite, chamosite in float, you are in the right ground. Typical habit: acicular, flakes. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify taneyamalite?+

Mohs hardness is 5-6. Luster: vitreous. The streak is light yellow, brown. Common colors include greenish yellow, grayish yellow.

Where is taneyamalite found?+

Notable localities include Ward Creek, near Cazadero, and along the Russian River, Sonoma Co., and Pacheco Pass, Santa Clara Co., California, USA; Taneyama mine, Kumamoto Prefecture, and the Iwaizawa mine, near Agano, Saitama Prefecture, Japan; Brezovia, Yugoslavia.

What minerals are found with taneyamalite?+

Taneyamalite commonly co-occurs with Quartz, Hematite, Chamosite, Caryopilite, Bannisterite, Braunite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does taneyamalite form in?+

Where it forms: In cracks in ferruginous chert, mafic rocks, and limestone subjected to blueschist facies metamorphism (Taneyama mine, Japan). Working float back to the host body is the standard way to chase a fresh occurrence.

What is taneyamalite used for?+

Taneyamalite is used in collector.

Find taneyamalite on the map

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