Malladrite is a rare sodium fluorosilicate typically found as a volcanic sublimated mineral in fumaroles. It often occurs as tiny, thin hexagonal plates or white crusts associated with other fluorine-bearing minerals. Because it is water-soluble and chemically unstable in humid environments, specimens should be stored in a dry, airtight container.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrarenull family

Malladrite

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this malladrite?

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 malladrite with a known reference. Malladrite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Malladrite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Malladrite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white.
5
Look at form & habit
Crystal system: trigonal. Typical habit: small hexagonal plates, crusts, or encrustations.

Often confused with

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

How to tell apart: Luster reads vitreous on Malladrite and vitreous to greasy on Cryolite.

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Often found alongside malladrite

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

All properties

Chemical formula: Na₂SiF₆
Mohs hardness: 2
Density: 2.8 g/cm³
Colors: Colorless White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Small Hexagonal Plates, Crusts, Or Encrustations
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Fumarolic Deposits in Volcanic Settings
Typical price: $50-300 per specimen

Where rockhounds find malladrite

Classic worldwide localities

Mount Vesuvius, Italy
Tolbachik volcano, Russia

Field-hunting tip

Look in fumarolic deposits in volcanic settings country — that is the host setting where malladrite typically forms. If you start seeing hieratite, sulfur, gypsum in float, you are in the right ground. Field specimens usually show a small hexagonal plates, crusts, or encrustations habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify malladrite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white.

Where is malladrite found?+

Notable localities include Mount Vesuvius, Italy; Tolbachik volcano, Russia.

How much is malladrite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is malladrite safe to handle?+

It contains toxic constituents. Contains fluorine and can release hazardous hydrogen fluoride gas if treated with acids or heated to high temperatures. Handle with care and avoid dust inhalation. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like malladrite?+

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

What minerals are found with malladrite?+

Malladrite commonly co-occurs with Hieratite, Sulfur, Gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does malladrite form in?+

Malladrite typically forms in fumarolic deposits in volcanic settings. Working float back to the host body is the standard way to chase a fresh occurrence.

What is malladrite used for?+

Malladrite is used in collector.

Find malladrite on the map

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