Roumaite is a rare member of the perrierite group found primarily in the alkaline rocks of the Langesundsfjord region. It typically appears as small, dark, opaque prismatic crystals and is primarily sought by advanced mineral collectors of rare-earth silicates.

Hardness

5-6

Mohs

Luster

Silky

Streak

White

Transparency

Transparent

mineralrarePerrierite Group family

Roumaite

Hardness: 5-6
Luster: Silky
Streak: White
Transparency: Transparent

No image

Is this roumaite?

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 roumaite with a known reference. Roumaite 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. Roumaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Roumaite typically shows a silky luster.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals.

Often found alongside roumaite

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

All properties

Chemical formula: (Ca,Na,☐)₃(Ca,REE,Na)₄(Nb,Ti)[Si₂O₇]₂(OH)F₃
Mohs hardness: 5-6
Density: 3.33 g/cm³
Colors: Colorless
Streak: White
Luster: Silky
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Nepheline Syenite Pegmatites

Where rockhounds find roumaite

Classic worldwide localities

Rouma, Langesundsfjord, Norway

Field-hunting tip

Look in nepheline syenite pegmatites country, the host setting where roumaite typically forms. If you start seeing aegirine, microcline, nepheline 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 roumaite?+

Mohs hardness is 5-6. It typically shows a silky luster. The streak is white. Common colors include colorless.

Where is roumaite found?+

Notable localities include Rouma, Langesundsfjord, Norway.

Is roumaite safe to handle?+

This mineral is radioactive. Contains thorium, which is radioactive. Handle with care, store away from other specimens, and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What minerals are found with roumaite?+

Roumaite commonly co-occurs with Aegirine, Microcline, Nepheline, Astrophyllite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does roumaite form in?+

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

What is roumaite used for?+

Roumaite is used in collector.

Find roumaite on the map

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