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, 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.