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, so Yarrowite leaves black, Covellite leaves lead gray to black.
How to tell apart: Streak differs, so Yarrowite leaves black, Chalcocite leaves lead-gray to black.
How to tell apart: Streak differs, so 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, 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
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
