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

2-2.5

Mohs

Luster

Metallic to submetallic

Streak

Orange

Transparency

Opaque

mineralrare

Arsiccioite

Hardness: 2-2.5
Luster: Metallic to submetallic
Streak: Orange
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 2-2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: orange.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic to submetallic.
4
Match the color range
Compare against the expected color range: red, internal reflections weak, deep red.
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.

mineral

Tennantite

Mohs 3-4.5

How to tell apart: Streak differs, so Arsiccioite leaves orange, Tennantite leaves reddish gray.

How to tell apart: Streak differs, so Arsiccioite leaves orange, Tetrahedrite leaves black to brown.

Compare →

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: AgHg₂TlAs₂S₆
Mohs hardness: 2-2.5
Density: 5.989 g/cm³
Colors: RedInternal reflections weakDeep red
Streak: Orange
Luster: Metallic to submetallic
Transparency: Opaque
Crystal system: Tetragonal
Crystal habit: Equant to subhedral crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In a lens of microcrystalline barite near the contact between schist and pyrite-rich dolostone

Where rockhounds find arsiccioite

Classic worldwide localities

Apuan Alps, Tuscany, Italy

Field-hunting tip

Where it forms: In a lens of microcrystalline barite near the contact between schist and pyrite-rich dolostone. If you start seeing protochabournéite, cinnabar, laffittite in float, you are in the right ground. Typical habit: equant to subhedral crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify arsiccioite?+

Mohs hardness is 2-2.5. Luster: metallic to submetallic. The streak is orange. Common colors include red, internal reflections weak, deep red.

Where is arsiccioite found?+

Notable localities include Apuan Alps, Tuscany, Italy.

Is arsiccioite safe to handle?+

Arsiccioite contains arsenic, mercury and thallium and calls for real care. Contains mercury, silver, thallium, and arsenic. Always wash hands after handling and avoid inhaling dust; store securely to avoid ingestion or contamination.

What rocks look like arsiccioite?+

Arsiccioite is most often confused with Tennantite, 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 Protochabournéite, Cinnabar, Laffittite, Pyrite, Realgar, Hg-bearing sphalerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does arsiccioite form in?+

Where it forms: In a lens of microcrystalline barite near the contact between schist and pyrite-rich dolostone. 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.