Tamaite is a rare manganese-bearing member of the pumpellyite group, typically occurring as fine fibrous or radiating acicular clusters. It is primarily identified by its characteristic brownish color and its occurrence in metamorphosed manganese deposits.

Hardness

Mohs

Luster

Vitreous to pearly

Streak

White

Transparency

Transparent

mineralrarePumpellyite Group family

Tamaite

Hardness: 4
Luster: Vitreous to pearly
Streak: White
Transparency: Transparent

No image

Is this tamaite?

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 tamaite with a known reference. Tamaite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to pearly.
4
Match the color range
Compare against the expected color range: colorless, pale yellowish brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: micaceous, platy.

Often found alongside tamaite

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

All properties

Chemical formula: (Ca,K,Na)xMn₆(Si,Al)₁₀O₂₄(OH)₄·nH₂O (x = 1-2; n = 7-11)
Mohs hardness: 4
Density: 2.85 g/cm³
Colors: ColorlessPale yellowish brown
Streak: White
Luster: Vitreous to pearly
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Micaceous, platy
Cleavage: Perfect on {001}
Rarity: Rare
Uses: Collector
Host rock: In veinlets to 1.5 mm in width in a weakly metamorphosed Mn ore deposit

Where rockhounds find tamaite

Classic worldwide localities

Shiromaru mine, near Okutama, Tama district, ~60 km from Tokyo, Japan

Field-hunting tip

Where it forms: In veinlets to 1.5 mm in width in a weakly metamorphosed Mn ore deposit. If you start seeing celsian, barian orthoclase, aegirine in float, you are in the right ground. Typical habit: micaceous, platy. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify tamaite?+

Mohs hardness is 4. Luster: vitreous to pearly. The streak is white. Common colors include colorless, pale yellowish brown.

Where is tamaite found?+

Notable localities include Shiromaru mine, near Okutama, Tama district, ~60 km from Tokyo, Japan.

What minerals are found with tamaite?+

Tamaite commonly co-occurs with Celsian, Barian orthoclase, Aegirine, Manganoan grossular, Andradite, Strontiopiemontite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does tamaite form in?+

Where it forms: In veinlets to 1.5 mm in width in a weakly metamorphosed Mn ore deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is tamaite used for?+

Tamaite is used in collector.

Find tamaite on the map

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