Perettiite-(Y) is an exceptionally rare yttrium manganese borosilicate mineral known primarily from alkaline pegmatites in the Zomba District of Malawi. It typically occurs as small, dark prismatic crystals embedded in matrix. Due to its rarity, it is highly sought after by advanced systematic mineral collectors.

Hardness

6-7

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrarenull family

Perettiite-(Y)

Hardness: 6-7
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this perettiite-(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 perettiite-(y) with a known reference. Perettiite-(Y) sits at Mohs 6-7 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Perettiite-(Y) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Perettiite-(Y) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: dark brown, black.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic crystals.

Often confused with

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

How to tell apart: Streak differs — Perettiite-(Y) leaves white, Allanite leaves gray; luster reads vitreous on Perettiite-(Y) and submetallic on Allanite.

Compare →

Often found alongside perettiite-(y)

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

All properties

Chemical formula: Y₂Mn₄Si₂B₈O₂₄
Mohs hardness: 6-7
Density: 4.15 g/cm³
Colors: Dark Brown Black
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Pegmatites
Typical price: $50-500 thumbnail

Where rockhounds find perettiite-(y)

Classic worldwide localities

Mount Malosa, Zomba District, Malawi

Field-hunting tip

Look in alkaline pegmatites country — that is the host setting where perettiite-(y) typically forms. If you start seeing quartz, microcline, aegirine in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify perettiite-(y)?+

Mohs hardness is 6-7. It typically shows a vitreous luster. The streak is white. Common colors include dark brown, black.

Where is perettiite-(y) found?+

Notable localities include Mount Malosa, Zomba District, Malawi.

How much is perettiite-(y) worth?+

Typical asking prices fall in the range of $50-500 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like perettiite-(y)?+

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

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

Perettiite-(Y) commonly co-occurs with Quartz, Microcline, Aegirine, Arfvedsonite, Zircon. Spotting any of these in float or country rock is a useful trip signal.

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

Perettiite-(Y) typically forms in alkaline pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is perettiite-(y) used for?+

Perettiite-(Y) is used in collector.

Find perettiite-(y) on the map

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