Weilite is a rare calcium arsenate mineral typically found as small, thin tabular crystals in hydrothermal deposits. It is structurally related to the monetite group and is primarily prized by advanced mineral collectors for its scarcity and aesthetic crystal form.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareMonetite Group family

Weilite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this weilite?

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 weilite with a known reference. Weilite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Weilite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Weilite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, thin plates, aggregates.

Often confused with

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

Often found alongside weilite

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

All properties

Chemical formula: CaHAsO₄
Mohs hardness: 2-3
Density: 3.31 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular Crystals, Thin Plates, Aggregates
Cleavage: Perfect On {010}
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $50-300 per specimen

Where rockhounds find weilite

Classic worldwide localities

Ste. Marie-aux-Mines, France
Johanngeorgenstadt, Germany
Jachymov, Czech Republic

Field-hunting tip

Look in hydrothermal veins country — that is the host setting where weilite typically forms. If you start seeing pharmacolite, picropharmacolite, haidingerite in float, you are in the right ground. Field specimens usually show a tabular crystals, thin plates, aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify weilite?+

Mohs hardness is 2-3. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless.

Where is weilite found?+

Notable localities include Ste. Marie-aux-Mines, France; Johanngeorgenstadt, Germany; Jachymov, Czech Republic.

How much is weilite 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 weilite safe to handle?+

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

What rocks look like weilite?+

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

What minerals are found with weilite?+

Weilite commonly co-occurs with Pharmacolite, Picropharmacolite, Haidingerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does weilite form in?+

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

What is weilite used for?+

Weilite is used in collector.

Find weilite on the map

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