Yarrowite is a rare copper sulfide mineral that typically forms as an alteration product of other copper minerals. It is best identified in laboratory settings via X-ray diffraction, as it is visually indistinguishable from its associate, covellite, often appearing as dark, metallic-lustered inclusions or fine-grained masses.
Is this yarrowite?
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 yarrowite with a known reference. Yarrowite sits at Mohs 1.5-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Yarrowite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Yarrowite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: indigo-blue, blackish-blue.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: platy crystals, granular.
Often confused with
Yarrowite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Yarrowite leaves black, Covellite leaves lead gray to black.
How to tell apart: Streak differs — Yarrowite leaves black, Chalcocite leaves lead-gray to black.
How to tell apart: Streak differs — Yarrowite leaves black, Djurleite leaves lead-gray.
Often found alongside yarrowite
Minerals reported to co-occur with yarrowite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₉S₈
- Mohs hardness
- 1.5-2
- Density
- 5.65 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Platy Crystals, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Sulfide Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find yarrowite
Classic worldwide localities
- Yarrow Creek, Alberta, Canada
- Leonard Mine, Butte, Montana, USA
Field-hunting tip
Look in hydrothermal sulfide deposits country — that is the host setting where yarrowite typically forms. If you start seeing covellite, bornite, chalcopyrite in float, you are in the right ground. Field specimens usually show a platy crystals, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find yarrowite on the map
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