Menchettiite is a rare antimony sulfide mineral that occurs primarily as acicular or fibrous needle-like crystals. It is typically found in low-temperature hydrothermal veins, often associated with stibnite, and was originally identified in the Apuan Alps region of Italy.

Hardness

2.5-3

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareStibnite Group family

Menchettiite

Hardness: 2.5-3
Luster: Metallic
Streak: Black
Transparency: Opaque

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Is this menchettiite?

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 menchettiite with a known reference. Menchettiite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: black.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: acicular to fibrous aggregates.

Often confused with

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

mineral

Stibnite

Mohs 2

How to tell apart: Streak differs, so Menchettiite leaves black, Stibnite leaves lead-gray.

How to tell apart: Streak differs, so Menchettiite leaves black, Berthierite leaves dark brownish gray.

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Often found alongside menchettiite

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

All properties

Chemical formula: Pb₅Mn₃Ag₂Sb₆As₄S₂₄
Mohs hardness: 2.5-3
Density: 5.146 g/cm³
Colors: Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Acicular to fibrous aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In a polymetallic (Ag-Mn-Pb-Zn) vein, replacement, and contact metamorphic mineral district

Where rockhounds find menchettiite

Classic worldwide localities

Level 890, Uchucchacua polymetallic deposit, Oyon district, Catajambo, Lima Department, Peru

Field-hunting tip

Where it forms: In a polymetallic (Ag-Mn-Pb-Zn) vein, replacement, and contact metamorphic mineral district. If you start seeing orpiment, quartz, calcite in float, you are in the right ground. Typical habit: acicular to fibrous aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify menchettiite?+

Mohs hardness is 2.5-3. Luster: metallic. The streak is black. Common colors include black.

Where is menchettiite found?+

Notable localities include Level 890, Uchucchacua polymetallic deposit, Oyon district, Catajambo, Lima Department, Peru.

Is menchettiite safe to handle?+

Menchettiite contains antimony, arsenic and lead and calls for real care. Contains antimony and manganese; avoid inhaling dust and wash hands thoroughly after handling to prevent ingestion of toxic heavy metals.

What rocks look like menchettiite?+

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

What minerals are found with menchettiite?+

Menchettiite commonly co-occurs with Orpiment, Quartz, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does menchettiite form in?+

Where it forms: In a polymetallic (Ag-Mn-Pb-Zn) vein, replacement, and contact metamorphic mineral district. Working float back to the host body is the standard way to chase a fresh occurrence.

What is menchettiite used for?+

Menchettiite is used in collector.

Find menchettiite on the map

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