Bertossaite is a very rare phosphate mineral belonging to the amblygonite group, typically found in highly fractionated pegmatites. It usually forms small bladed or granular clusters and is prized by advanced collectors of rare phosphate species due to its extremely limited global occurrence.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Semitransparent

mineralrareAmblygonite Group family

Bertossaite

Hardness: 6
Luster: Vitreous
Streak: White
Transparency: Semitransparent

Is this bertossaite?

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 bertossaite with a known reference. Bertossaite sits at Mohs 6, 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.
4
Match the color range
Compare against the expected color range: light pink.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: bladed crystals, granular masses.

Often confused with

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

Often found alongside bertossaite

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

All properties

Chemical formula: Li₂CaAl₄(PO₄)₄(OH)₄
Mohs hardness: 6
Density: 3.10 g/cm³
Colors: Light pink
Streak: White
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Orthorhombic
Crystal habit: Bladed crystals, granular masses
Cleavage: On {100}, good
Rarity: Rare
Uses: Collector
Host rock: Thought to be formed during a late calcium-rich phase of mineralization in a lithium-bearing granite pegmatite

Where rockhounds find bertossaite

Classic worldwide localities

Buranga pegmatite, near Gatumba, Rwanda

Field-hunting tip

Where it forms: Thought to be formed during a late calcium-rich phase of mineralization in a lithium-bearing granite pegmatite. If you start seeing amblygonite, lazulite-scorzalite, augelite in float, you are in the right ground. Typical habit: bladed crystals, granular masses. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bertossaite?+

Mohs hardness is 6. Luster: vitreous. The streak is white. Common colors include light pink.

Where is bertossaite found?+

Notable localities include Buranga pegmatite, near Gatumba, Rwanda.

What rocks look like bertossaite?+

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

What minerals are found with bertossaite?+

Bertossaite commonly co-occurs with Amblygonite, Lazulite-scorzalite, Augelite, Brazilianite, Apatite, Crandallite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bertossaite form in?+

Where it forms: Thought to be formed during a late calcium-rich phase of mineralization in a lithium-bearing granite pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is bertossaite used for?+

Bertossaite is used in collector.

Find bertossaite on the map

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