Andreadiniite is a rare sulfosalt mineral found in hydrothermal deposits. It typically occurs as small, metallic, tabular crystals and is primarily sought after by advanced collectors focusing on rare lead-silver-copper sulfosalts.

Hardness

~3.5

Mohs

Luster

Metallic

Transparency

Opaque

mineralrare

Andreadiniite

Hardness: ~3.5
Luster: Metallic
Transparency: Opaque

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Is this andreadiniite?

4-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 andreadiniite with a known reference. Andreadiniite sits at Mohs ~3.5, softer than the next harder reference, harder than the previous one.
2
Read the luster
Hold the specimen under a strong light. Luster: metallic.
3
Match the color range
Compare against the expected color range: lead-gray.
4
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals.

Often confused with

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

mineral

Freieslebenite

Mohs 2-2.5

How to tell apart: Andreadiniite is noticeably harder (Mohs ~3.5 vs. 2-2.5).

Often found alongside andreadiniite

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

All properties

Chemical formula: CuHgAg₇Pb₇Sb₂₄S₄₈
Mohs hardness: ~3.5
Density: 5.36 g/cm³
Colors: Lead-gray
Luster: Metallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Tabular crystals
Rarity: Rare
Uses: Collector
Host rock: In a hydrothermal quartz vein in metadolostone

Where rockhounds find andreadiniite

Classic worldwide localities

Sant’Olga tunnel, Monte Arsiccio mine, Stazzema, Apuan Alps, Tuscany, Italy

Field-hunting tip

Where it forms: In a hydrothermal quartz vein in metadolostone. If you start seeing sphalerite, stibnite, boscardinite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify andreadiniite?+

Mohs hardness is ~3.5. Luster: metallic. Common colors include lead-gray.

Where is andreadiniite found?+

Notable localities include Sant’Olga tunnel, Monte Arsiccio mine, Stazzema, Apuan Alps, Tuscany, Italy.

Is andreadiniite safe to handle?+

Andreadiniite contains antimony, copper, lead and mercury and calls for real care. Contains lead and silver; handle with care and wash hands thoroughly after handling. Do not ingest or inhale dust.

What rocks look like andreadiniite?+

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

What minerals are found with andreadiniite?+

Andreadiniite commonly co-occurs with Sphalerite, Stibnite, Boscardinite, Protochabournéite, Routhierite, Hg-rich tetrahedrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does andreadiniite form in?+

Where it forms: In a hydrothermal quartz vein in metadolostone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is andreadiniite used for?+

Andreadiniite is used in collector.

Find andreadiniite on the map

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