Coulsonite is a rare vanadium-rich member of the spinel group, typically found in metamorphosed iron deposits or as an accessory mineral in mafic rocks. It is physically similar to magnetite and often requires analytical testing for definitive identification due to its dark, non-descript appearance. Collectors seek it primarily as a rare end-member mineral from classic iron-ore localities.
Is this coulsonite?
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 coulsonite with a known reference. Coulsonite sits at Mohs 4.5-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark brown to black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: blue gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral, massive, granular.
Often confused with
Coulsonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Coulsonite leaves dark brown to black, Magnetite leaves black.
How to tell apart: Streak differs, so Coulsonite leaves dark brown to black, Chromite leaves brown.
How to tell apart: Franklinite is the harder of the two (Mohs ~6 vs. 4.5-5); streak differs, so Coulsonite leaves dark brown to black, Franklinite leaves reddish brown to black.
Often found alongside coulsonite
Minerals reported to co-occur with coulsonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeV₂O₄
- Mohs hardness
- 4.5-5
- Density
- 5.17-5.20 g/cm³
- Colors
- Streak
- Dark brown to black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Octahedral, massive, granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Geological study
- Host rock
- In veinlets of magnetite, with silicate minerals, cutting metamorphosed andesite (Buena Vista Hills, Nevada, USA); exsolved from magnetite in a mantle xenolith in basalt (Panzhihua, China)
Where rockhounds find coulsonite
Classic worldwide localities
- Buena Vista Hills, 32 km southeast of Lovelock, Mineral Basin district, Pershing Co., Nevada, USA
- Kalgoorlie, Western Australia
- Dublahera, Singhbum, Bihar, India
- Found at Panzhihua, Sichuan Province, China
Field-hunting tip
Where it forms: In veinlets of magnetite, with silicate minerals, cutting metamorphosed andesite (Buena Vista Hills, Nevada, USA); exsolved from magnetite in a mantle xenolith in basalt (Panzhihua, China). If you start seeing magnetite, scapolite, apatite in float, you are in the right ground. Typical habit: octahedral, massive, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify coulsonite?+
Where is coulsonite found?+
Is coulsonite safe to handle?+
What rocks look like coulsonite?+
What minerals are found with coulsonite?+
What kind of rock does coulsonite form in?+
What is coulsonite used for?+
Find coulsonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
