Oyonite is a rare silver manganese lead sulfosalt that forms black non-euhedral crystals. It was approved as a distinct mineral species in 2018. It was first described from the Nivel 890, Uchucchacua deposit, Oyon district, Catajambo, Lima Department, Peru.

Hardness

3-3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareMineraloid family

Oyonite

Hardness: 3-3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this oyonite?

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

Often confused with

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

sedimentary

Coal

Mohs 0.5-2.5

How to tell apart: Luster reads metallic on Oyonite and dull to submetallic on Coal.

How to tell apart: Streak differs, so Oyonite leaves black, Jet leaves brown; luster reads metallic on Oyonite and resinous on Jet.

Compare →

Often found alongside oyonite

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

All properties

Chemical formula: Ag₃Mn₂Pb₄Sb₇As₄S₂₄
Mohs hardness: 3-3.5
Density: 5.275 g/cm³
Colors: Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Non-euhedral Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Sedimentary Coal Beds

Where rockhounds find oyonite

Classic worldwide localities

Oyon, Peru

Field-hunting tip

Look in sedimentary coal beds country, the host setting where oyonite typically forms. If you start seeing coal, pyrite in float, you are in the right ground. Field specimens usually show a non-euhedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify oyonite?+

Mohs hardness is 3-3.5. It typically shows a metallic luster. The streak is black. Common colors include black.

Where is oyonite found?+

Notable localities include Oyon, Peru.

Is oyonite safe to handle?+

It contains toxic constituents. Contains antimony, arsenic and lead, which are toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like oyonite?+

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

What minerals are found with oyonite?+

Oyonite commonly co-occurs with Coal, Pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does oyonite form in?+

Oyonite typically forms in sedimentary coal beds. Working float back to the host body is the standard way to chase a fresh occurrence.

What is oyonite used for?+

Oyonite is used in collector.

Find oyonite on the map

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