Epistolite is a rare mineral found primarily in alkaline igneous rocks like nepheline syenites. It is typically identified by its distinct micaceous or platy appearance, often forming flexible, pearly lamellae that resemble mica but with different chemical properties.

Hardness

3.5

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrareLomonosovite Group family

Epistolite

Hardness: 3.5
Luster: Pearly
Streak: White
Transparency: Translucent

Is this epistolite?

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 epistolite with a known reference. Epistolite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Epistolite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Epistolite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: white, gray, pink, yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: lamellar crystals, tabular, micaceous flakes.

Often confused with

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

mineral

Lomonosovite

Mohs 3-4

How to tell apart: Streak differs — Epistolite leaves white, Lomonosovite leaves yellowish brown; luster reads pearly on Epistolite and vitreous on Lomonosovite.

Often found alongside epistolite

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

All properties

Chemical formula: Na₄TiNb₂(Si₂O₇)₂O₂(OH)₂·4H₂O
Mohs hardness: 3.5
Density: 2.9 g/cm³
Colors: White Gray Pink Yellow
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Lamellar Crystals, Tabular, Micaceous Flakes
Cleavage: Perfect Basal
Rarity: Rare
Uses: Collector
Host rock: Nepheline Syenite Pegmatites
Typical price: $20-150 per specimen depending on size and quality

Where rockhounds find epistolite

Classic worldwide localities

Kola Peninsula, Russia
Mont Saint-Hilaire, Canada

Field-hunting tip

Look in nepheline syenite pegmatites country — that is the host setting where epistolite typically forms. If you start seeing aegirine, microcline, nepheline in float, you are in the right ground. Field specimens usually show a lamellar crystals, tabular, micaceous flakes habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify epistolite?+

Mohs hardness is 3.5. It typically shows a pearly luster. The streak is white. Common colors include white, gray, pink, yellow.

Where is epistolite found?+

Notable localities include Kola Peninsula, Russia; Mont Saint-Hilaire, Canada.

How much is epistolite worth?+

Typical asking prices fall in the range of $20-150 per specimen depending on size and quality. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like epistolite?+

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

What minerals are found with epistolite?+

Epistolite commonly co-occurs with Aegirine, Microcline, Nepheline, Arfvedsonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does epistolite form in?+

Epistolite typically forms in nepheline syenite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is epistolite used for?+

Epistolite is used in collector.

Find epistolite on the map

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