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, 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.