Gaultite is an extremely rare gallium-molybdenum sulfide mineral discovered in the alkaline rocks of Mont Saint-Hilaire. It typically forms as small, colorless to pale yellow tetrahedral crystals associated with sodalite and analcime. Due to its extreme rarity and very limited occurrence, it is highly sought after by advanced micromount collectors.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Gaultite

Hardness: 3.5
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this gaultite?

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 gaultite with a known reference. Gaultite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Gaultite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Gaultite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, pale yellow.
5
Look at form & habit
Crystal system: cubic. Typical habit: tetrahedral crystals.

Often confused with

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

mineral

Sodalite

Mohs 5.5-6

How to tell apart: Sodalite is the harder of the two (Mohs 5.5-6 vs. 3.5).

How to tell apart: Analcite is the harder of the two (Mohs 5-5.5 vs. 3.5).

Compare →

Often found alongside gaultite

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

All properties

Chemical formula: Ga₄Mo₄S₁₆
Mohs hardness: 3.5
Density: 2.44 g/cm³
Colors: Colorless White Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Cubic
Crystal habit: Tetrahedral Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks
Typical price: $200-800 per specimen

Where rockhounds find gaultite

Classic worldwide localities

Mont Saint-Hilaire, Quebec, Canada

Field-hunting tip

Look in alkaline igneous rocks country — that is the host setting where gaultite typically forms. If you start seeing sodalite, analcime, microcline in float, you are in the right ground. Field specimens usually show a tetrahedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify gaultite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, pale yellow.

Where is gaultite found?+

Notable localities include Mont Saint-Hilaire, Quebec, Canada.

How much is gaultite worth?+

Typical asking prices fall in the range of $200-800 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like gaultite?+

Gaultite is most often confused with Sodalite, Analcite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with gaultite?+

Gaultite commonly co-occurs with Sodalite, Analcime, Microcline, Aegirine, Eudialyte. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does gaultite form in?+

Gaultite typically forms in alkaline igneous rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is gaultite used for?+

Gaultite is used in collector.

Find gaultite on the map

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