Fabrièsite is a very rare phosphate mineral typically occurring as small, clear, tabular crystals. It is best known from the unique alkaline environment of the Mont Saint-Hilaire complex in Quebec, where it forms in vugs associated with other rare minerals.

Hardness

4.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareGorceixite Group family

Fabrièsite

Hardness: 4.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this fabrièsite?

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 fabrièsite with a known reference. Fabrièsite sits at Mohs 4.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Fabrièsite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Fabrièsite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, yellowish.
5
Look at form & habit
Crystal system: trigonal. Typical habit: tabular crystals.

Often confused with

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

Often found alongside fabrièsite

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

All properties

Chemical formula: NaAl₃(PO₄)₂(OH)₄
Mohs hardness: 4.5
Density: 3.32 g/cm³
Colors: Colorless White Yellowish
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Tabular Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks
Typical price: $50-300 per specimen

Where rockhounds find fabrièsite

Classic worldwide localities

Mont Saint-Hilaire, Quebec, Canada

Field-hunting tip

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

Common questions

How do you identify fabrièsite?+

Mohs hardness is 4.5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, yellowish.

Where is fabrièsite found?+

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

How much is fabrièsite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like fabrièsite?+

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

What minerals are found with fabrièsite?+

Fabrièsite commonly co-occurs with Quartz, Albite, Aegirine, Microcline. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fabrièsite form in?+

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

What is fabrièsite used for?+

Fabrièsite is used in collector.

Find fabrièsite on the map

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