Agmantinite is a rare silver arsenic sulfide that occurs primarily as massive aggregates within silver-rich hydrothermal vein systems. It is physically similar to other silver sulfosalts and is typically identified through its metallic luster, orange-red streak, and association with other silver-bearing minerals.
Is this agmantinite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch agmantinite with a known reference. Agmantinite sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: red.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: orange-red.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive, granular, or anhedral grains.
Often confused with
Agmantinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Agmantinite leaves red, Proustite leaves vermilion.
How to tell apart: Streak differs, so Agmantinite leaves red, Pyrargyrite leaves purplish red.
How to tell apart: Streak differs, so Agmantinite leaves red, Stephanite leaves iron-black; luster reads adamantine on Agmantinite and metallic on Stephanite.
Often found alongside agmantinite
Minerals reported to co-occur with agmantinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₂MnSnS₄
- Mohs hardness
- 2-2.5
- Density
- 4.608 g/cm³
- Colors
- Streak
- Red
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Massive, granular, or anhedral grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the alabandite zone of a polymetallic hydrothermal mineral deposit
Where rockhounds find agmantinite
Classic worldwide localities
- Uchucchacua deposit, Oyon district, Catajambo, Lima Department, Peru
Field-hunting tip
Where it forms: In the alabandite zone of a polymetallic hydrothermal mineral deposit. If you start seeing calcite, quartz, manganoquadratite in float, you are in the right ground. Typical habit: massive, granular, or anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify agmantinite?+
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Find agmantinite on the map
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