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, 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.