Aliettite is a rare regular mixed-layer silicate mineral consisting of alternating talc-like and saponite-like layers. It typically forms soft, platy, or scaly masses in hydrothermal environments and is best identified through X-ray diffraction due to its macroscopic similarity to other clay minerals.

Hardness

1-2

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrareSmectite Group family

Aliettite

Hardness: 1-2
Luster: Pearly
Streak: White
Transparency: Translucent

Is this aliettite?

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 aliettite with a known reference. Aliettite sits at Mohs 1-2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Aliettite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Aliettite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: white, gray, yellowish, greenish.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy aggregates, scaly masses.

Often confused with

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

How to tell apart: Luster reads pearly on Aliettite and dull on Saponite.

Often found alongside aliettite

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

All properties

Chemical formula: (Ca,Na)₀.₂Mg₆(Si,Al)₈O₂₀(OH)₄·4H₂O
Mohs hardness: 1-2
Density: 2.1-2.3 g/cm³
Colors: White Gray Yellowish Greenish
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Aggregates, Scaly Masses
Cleavage: Perfect Basal
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Hydrothermal Veins in Mafic and Ultramafic Rocks
Typical price: $20-100 per specimen depending on size and rarity

Where rockhounds find aliettite

Classic worldwide localities

Rossena, Italy
Banská Štiavnica, Slovakia
Milos, Greece

Field-hunting tip

Look in hydrothermal veins in mafic and ultramafic rocks country — that is the host setting where aliettite typically forms. If you start seeing calcite, dolomite, quartz in float, you are in the right ground. Field specimens usually show a platy aggregates, scaly masses habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify aliettite?+

Mohs hardness is 1-2. It typically shows a pearly luster. The streak is white. Common colors include white, gray, yellowish, greenish.

Where is aliettite found?+

Notable localities include Rossena, Italy; Banská Štiavnica, Slovakia; Milos, Greece.

How much is aliettite worth?+

Typical asking prices fall in the range of $20-100 per specimen depending on size and rarity. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like aliettite?+

Aliettite is most often confused with Talc, Saponite, Vermiculite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with aliettite?+

Aliettite commonly co-occurs with Calcite, Dolomite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does aliettite form in?+

Aliettite typically forms in hydrothermal veins in mafic and ultramafic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is aliettite used for?+

Aliettite is used in collector, scientific research.

Find aliettite on the map

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