Bussyite-(Y) is an exceptionally rare silicate mineral primarily found in agpaitic alkaline igneous rocks. It typically forms small, prismatic to tabular crystals and is highly prized by advanced mineral collectors for its complexity and scarcity.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent to translucent

mineralrareGaidonnayite Group family

Bussyite-(Y)

Hardness: ~4
Luster: Vitreous
Streak: White
Transparency: Transparent to translucent

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Is this bussyite-(y)?

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 bussyite-(y) with a known reference. Bussyite-(Y) sits at Mohs ~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.
4
Match the color range
Compare against the expected color range: brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic to tabular crystals.

Often confused with

Bussyite-(Y) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Gaidonnayite

Mohs ~5

How to tell apart: Gaidonnayite is the harder of the two (Mohs ~5 vs. ~4).

How to tell apart: Eudialyte is the harder of the two (Mohs 5-6 vs. ~4).

Compare →

Often found alongside bussyite-(y)

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

All properties

Chemical formula: (Y,REE,Ca)₃(Na,Ca)₆MnSi₉Be₅(O,F,OH)₃₄
Mohs hardness: ~4
Density: 3.11 g/cm³
Colors: Brown
Streak: White
Luster: Vitreous
Transparency: Transparent to translucent
Crystal system: Monoclinic
Crystal habit: Prismatic to tabular crystals
Cleavage: Perfect on {101}
Rarity: Rare
Uses: Collector
Host rock: A late-stage hydrothermal product in alkaline pegmatite

Where rockhounds find bussyite-(y)

Classic worldwide localities

Poudrette quarry (level 7), Mont Saint-Hilaire, Rouville County, Quebec, Canada

Field-hunting tip

Where it forms: A late-stage hydrothermal product in alkaline pegmatite. If you start seeing analcime, microcline, sérandite in float, you are in the right ground. Typical habit: prismatic to tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bussyite-(y)?+

Mohs hardness is ~4. Luster: vitreous. The streak is white. Common colors include brown.

Where is bussyite-(y) found?+

Notable localities include Poudrette quarry (level 7), Mont Saint-Hilaire, Rouville County, Quebec, Canada.

Is bussyite-(y) safe to handle?+

Bussyite-(Y) contains beryllium. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like bussyite-(y)?+

Bussyite-(Y) is most often confused with Gaidonnayite, Eudialyte. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with bussyite-(y)?+

Bussyite-(Y) commonly co-occurs with Analcime, Microcline, Sérandite, Calcite, Cappelenite-, Catapleiite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bussyite-(y) form in?+

Where it forms: A late-stage hydrothermal product in alkaline pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is bussyite-(y) used for?+

Bussyite-(Y) is used in collector.

Find bussyite-(y) on the map

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