Asbecasite is an exceptionally rare beryllium-arsenic silicate found primarily in the Lengenbach Quarry of Switzerland. It typically occurs as small, tabular, yellowish-brown crystals embedded within dolomitic marble or associated with complex sulfosalt minerals.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrare

Asbecasite

Hardness: 6
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this asbecasite?

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 asbecasite with a known reference. Asbecasite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Asbecasite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Asbecasite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-brown, brown.
5
Look at form & habit
Crystal system: trigonal. Typical habit: tabular crystals, granular masses.

Often confused with

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

mineral

Titanite

Mohs 5-5.5

How to tell apart: Luster reads vitreous on Asbecasite and adamantine on Titanite.

How to tell apart: Dalyite is the harder of the two (Mohs 7-7.5 vs. 6).

Compare →

Often found alongside asbecasite

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

All properties

Chemical formula: Ca₃TiAs₆Be₂Si₂O₂₀
Mohs hardness: 6
Density: 4.21 g/cm³
Colors: Yellow Yellow-brown Brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Tabular Crystals, Granular Masses
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Dolomitic Marble, Hydrothermal Veins
Typical price: $50-300 per specimen

Where rockhounds find asbecasite

Classic worldwide localities

Binntal, Valais, Switzerland
Cuasso al Monte, Lombardy, Italy

Field-hunting tip

Look in dolomitic marble, hydrothermal veins country — that is the host setting where asbecasite typically forms. If you start seeing sartorite, baotite, cafarsite in float, you are in the right ground. Field specimens usually show a tabular crystals, granular masses habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify asbecasite?+

Mohs hardness is 6. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellow-brown, brown.

Where is asbecasite found?+

Notable localities include Binntal, Valais, Switzerland; Cuasso al Monte, Lombardy, Italy.

How much is asbecasite 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 asbecasite safe to handle?+

It contains toxic constituents. Contains arsenic, a toxic element. Handle with care, avoid creating dust, and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like asbecasite?+

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

What minerals are found with asbecasite?+

Asbecasite commonly co-occurs with Sartorite, Baotite, Cafarsite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does asbecasite form in?+

Asbecasite typically forms in dolomitic marble, hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is asbecasite used for?+

Asbecasite is used in collector.

Find asbecasite on the map

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