Arsiccioite is an extremely rare sulfosalt mineral found in the Apuan Alps of Italy. It occurs as small, black, metallic crystals typically associated with mercury and thallium-bearing minerals in hydrothermal vein systems.

Hardness

3.5-4

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrarenull family

Arsiccioite

Hardness: 3.5-4
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this arsiccioite?

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 arsiccioite with a known reference. Arsiccioite sits at Mohs 3.5-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Arsiccioite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Arsiccioite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: black.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: equant to subhedral crystals.

Often confused with

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

Often found alongside arsiccioite

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

All properties

Chemical formula: HgAgTlAs₂S₆
Mohs hardness: 3.5-4
Density: 4.86 g/cm³
Colors: Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Tetragonal
Crystal habit: Equant to Subhedral Crystals
Cleavage: None Observed
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Metamorphic Rocks
Typical price: $200-1000+ per specimen

Where rockhounds find arsiccioite

Classic worldwide localities

Apuan Alps, Tuscany, Italy

Field-hunting tip

Look in hydrothermal veins in metamorphic rocks country — that is the host setting where arsiccioite typically forms. If you start seeing cinnabar, realgar, pyrite in float, you are in the right ground. Field specimens usually show a equant to subhedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify arsiccioite?+

Mohs hardness is 3.5-4. It typically shows a metallic luster. The streak is black. Common colors include black.

Where is arsiccioite found?+

Notable localities include Apuan Alps, Tuscany, Italy.

How much is arsiccioite worth?+

Typical asking prices fall in the range of $200-1000+ per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is arsiccioite safe to handle?+

It contains toxic constituents. Contains mercury, silver, thallium, and arsenic. Always wash hands after handling and avoid inhaling dust; store securely to avoid ingestion or contamination. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like arsiccioite?+

Arsiccioite is most often confused with Tetrahedrite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with arsiccioite?+

Arsiccioite commonly co-occurs with Cinnabar, Realgar, Pyrite, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does arsiccioite form in?+

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

What is arsiccioite used for?+

Arsiccioite is used in collector.

Find arsiccioite on the map

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