Mckinstryite is a rare silver-copper sulfide that is typically found in low-temperature hydrothermal veins. It is most easily identified by its characteristic iron-black to steel-gray color and metallic luster, though it is often indistinguishable from other silver sulfides without microscopic or chemical analysis.
Is this mckinstryite?
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 mckinstryite with a known reference. Mckinstryite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Mckinstryite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Mckinstryite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: iron-black, steel-gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: anhedral, massive, or as inclusions within other sulfides.
Often confused with
Mckinstryite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside mckinstryite
Minerals reported to co-occur with mckinstryite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ag,Cu)₂S
- Mohs hardness
- 2.5
- Density
- 6.8 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Anhedral, Massive, Or as Inclusions Within Other Sulfides
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Low-temperature Hydrothermal Silver-base Metal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find mckinstryite
Classic worldwide localities
- Chihuahua, Mexico
- Galena, Kansas, USA
- Freiberg, Germany
- Kutná Hora, Czech Republic
Field-hunting tip
Look in low-temperature hydrothermal silver-base metal veins country — that is the host setting where mckinstryite typically forms. If you start seeing acanthite, galena, chalcopyrite in float, you are in the right ground. Field specimens usually show a anhedral, massive, or as inclusions within other sulfides habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mckinstryite?+
Where is mckinstryite found?+
How much is mckinstryite worth?+
Is mckinstryite safe to handle?+
What rocks look like mckinstryite?+
What minerals are found with mckinstryite?+
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Find mckinstryite on the map
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