Rouvilleite is a very rare sodium-calcium carbonate fluoride mineral discovered in the alkaline rocks of Mont Saint-Hilaire. It typically forms small, colorless to white hexagonal tabular crystals that are difficult to distinguish from other carbonates without laboratory analysis. Specimens are highly prized by mineral collectors due to the restricted number of global occurrences.

Hardness

3-4

Mohs

Luster

Vitreous to waxy

Streak

White

Transparency

Transparent to translucent

mineralrare

Rouvilleite

Hardness: 3-4
Luster: Vitreous to waxy
Streak: White
Transparency: Transparent to translucent

Is this rouvilleite?

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 rouvilleite with a known reference. Rouvilleite sits at Mohs 3-4, 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 waxy.
4
Match the color range
Compare against the expected color range: colorless, reddish brown, tan.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: irregular grains.

Often confused with

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

Often found alongside rouvilleite

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

All properties

Chemical formula: Na₃Ca₂(CO₃)₃F
Mohs hardness: 3-4
Density: 2.67-2.73 g/cm³
Colors: Colorless Reddish brown Tan
Streak: White
Luster: Vitreous to waxy
Transparency: Transparent to translucent
Crystal system: Monoclinic
Crystal habit: Irregular grains
Cleavage: Good on {001}; imperfect on {010}
Rarity: Rare
Uses: Collector
Host rock: In a sodalite xenolith in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada); in a differentiated alkalic massif (Lovozero massif, Kola Peninsula, Russia)

Where rockhounds find rouvilleite

Classic worldwide localities

Mont Saint-Hilaire, Quebec, Canada
Mt. Alluaiv, Lovozero massif, Kola Peninsula, Russia

Field-hunting tip

Where it forms: In a sodalite xenolith in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada); in a differentiated alkalic massif (Lovozero massif, Kola Peninsula, Russia). If you start seeing kupletskite, villiaumite, aegirine in float, you are in the right ground. Typical habit: irregular grains. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify rouvilleite?+

Mohs hardness is 3-4. Luster: vitreous to waxy. The streak is white. Common colors include colorless, reddish brown, tan.

Where is rouvilleite found?+

Notable localities include Mont Saint-Hilaire, Quebec, Canada; Mt. Alluaiv, Lovozero massif, Kola Peninsula, Russia.

What rocks look like rouvilleite?+

Rouvilleite is most often confused with Dawsonite, Calcite, Shortite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with rouvilleite?+

Rouvilleite commonly co-occurs with Kupletskite, Villiaumite, Aegirine, Microcline, Cancrinite, Analcime. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does rouvilleite form in?+

Where it forms: In a sodalite xenolith in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada); in a differentiated alkalic massif (Lovozero massif, Kola Peninsula, Russia). Working float back to the host body is the standard way to chase a fresh occurrence.

What is rouvilleite used for?+

Rouvilleite is used in collector.

Find rouvilleite on the map

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