Cuprospinel is a rare member of the spinel group, typically occurring as a secondary mineral in volcanic fumaroles or oxidizing ore deposits. Collectors prize it for its metallic luster and distinct octahedral habit, though it is often difficult to distinguish from common magnetite without chemical analysis.
Is this cuprospinel?
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 cuprospinel with a known reference. Cuprospinel sits at Mohs 6.5-7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: cubic. Typical habit: irregular grains.
Often confused with
Cuprospinel vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cuprospinel leaves black, Franklinite leaves reddish brown to black.
How to tell apart: Cuprospinel is noticeably harder (Mohs 6.5-7 vs. 5.5); streak differs, so Cuprospinel leaves black, Chromite leaves brown.
Often found alongside cuprospinel
Minerals reported to co-occur with cuprospinel. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuFe₂O₄
- Mohs hardness
- 6.5-7
- Density
- 5-5.2 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Irregular grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In highly oxidized material, once spontaneously ignited, in an ore dump
Where rockhounds find cuprospinel
Classic worldwide localities
- Consolidated Rambler Mines Limited, near Baie Verte, Newfoundland, Canada (type locality)
Field-hunting tip
Where it forms: In highly oxidized material, once spontaneously ignited, in an ore dump. If you start seeing pyrite, chalcopyrite, sphalerite in float, you are in the right ground. Typical habit: irregular grains. Train your eye for that shape before scanning the outcrop.
Common questions
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Find cuprospinel on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
