Bonacinaite is a rare scandium arsenate mineral discovered in alpine clefts. It is typically found as small, colorless to white prismatic crystals occurring alongside accessory minerals like anatase and hematite in hydrothermal vein environments.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Bonacinaite

Hardness: 3-4
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this bonacinaite?

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 bonacinaite with a known reference. Bonacinaite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Bonacinaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Bonacinaite 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: tetragonal. Typical habit: prismatic crystals, equant grains.

Often confused with

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

mineral

Scorodite

Mohs 3.5-4

How to tell apart: Luster reads vitreous on Bonacinaite and vitreous to sub-adamantine on Scorodite.

Often found alongside bonacinaite

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

All properties

Chemical formula: Sc(AsO₄)·2H₂O
Mohs hardness: 3-4
Density: 3.59 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Tetragonal
Crystal habit: Prismatic Crystals, Equant Grains
Cleavage: Distinct
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Pegmatites
Typical price: $100-500 per specimen

Where rockhounds find bonacinaite

Classic worldwide localities

Baveno, Piedmont, Italy
Pizzo Cervandone, Italy

Field-hunting tip

Look in hydrothermal veins in pegmatites country — that is the host setting where bonacinaite typically forms. If you start seeing quartz, k-feldspar, hematite in float, you are in the right ground. Field specimens usually show a prismatic crystals, equant grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bonacinaite?+

Mohs hardness is 3-4. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless.

Where is bonacinaite found?+

Notable localities include Baveno, Piedmont, Italy; Pizzo Cervandone, Italy.

How much is bonacinaite worth?+

Typical asking prices fall in the range of $100-500 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is bonacinaite safe to handle?+

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

What rocks look like bonacinaite?+

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

What minerals are found with bonacinaite?+

Bonacinaite commonly co-occurs with Quartz, K-feldspar, Hematite, Anatase. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bonacinaite form in?+

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

What is bonacinaite used for?+

Bonacinaite is used in collector.

Find bonacinaite on the map

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