Perlialite is an exceptionally rare zeolite-group mineral often occurring in alkaline pegmatites. Collectors look for its characteristic hexagonal prisms, which are most notably found in the unique mineral environment of Mont Saint-Hilaire.

Hardness

4-5

Mohs

Luster

Pearly

Streak

White

Transparency

Semitransparent

mineralrareZeolite Group family

Perlialite

Hardness: 4-5
Luster: Pearly
Streak: White
Transparency: Semitransparent

Is this perlialite?

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 perlialite with a known reference. Perlialite 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. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: pearly.
4
Match the color range
Compare against the expected color range: pearl white.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: prismatic crystals.

Often confused with

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

How to tell apart: Luster reads pearly on Perlialite and vitreous, pearly, or greasy on Cancrinite.

How to tell apart: Luster reads pearly on Perlialite and vitreous to greasy on Nepheline.

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Often found alongside perlialite

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

All properties

Chemical formula: K₉NaCa(Si₂₄Al₁₂)O₇₂·15H₂O
Mohs hardness: 4-5
Density: 2.14 g/cm³
Colors: Pearl white
Streak: White
Luster: Pearly
Transparency: Semitransparent
Crystal system: Hexagonal
Crystal habit: Prismatic crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In nepheline-microcline and sodalite-astrophyllite veins in nepheline-feldspar and sodalite-microcline pegmatites in a differentiated alkalic massif (Khibiny massif, Russia)

Where rockhounds find perlialite

Classic worldwide localities

Mts. Eveslogchorr and Yukspor, Khibiny massif, Kola Peninsula, and in the Murun massif, southwest of Olekminsk, Yakutia, Russia

Field-hunting tip

Where it forms: In nepheline-microcline and sodalite-astrophyllite veins in nepheline-feldspar and sodalite-microcline pegmatites in a differentiated alkalic massif (Khibiny massif, Russia). If you start seeing pectolite, kalsilite, aegirine in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify perlialite?+

Mohs hardness is 4-5. Luster: pearly. The streak is white. Common colors include pearl white.

Where is perlialite found?+

Notable localities include Mts. Eveslogchorr and Yukspor, Khibiny massif, Kola Peninsula, and in the Murun massif, southwest of Olekminsk, Yakutia, Russia.

What rocks look like perlialite?+

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

What minerals are found with perlialite?+

Perlialite commonly co-occurs with Pectolite, Kalsilite, Aegirine, Wadeite, Yuksporite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does perlialite form in?+

Where it forms: In nepheline-microcline and sodalite-astrophyllite veins in nepheline-feldspar and sodalite-microcline pegmatites in a differentiated alkalic massif (Khibiny massif, Russia). Working float back to the host body is the standard way to chase a fresh occurrence.

What is perlialite used for?+

Perlialite is used in collector.

Find perlialite on the map

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