Manganochromite is a rare member of the spinel group characterized by its high manganese and chromium content. It typically occurs as black, opaque octahedral crystals or massive aggregates within metamorphosed manganese ore bodies. Collectors look for it in high-grade metamorphic environments, often associated with other manganese-rich oxide minerals.
Is this manganochromite?
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 manganochromite with a known reference. Manganochromite sits at Mohs 5.5, 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: grayish black.
- 5Look at form & habitCrystal system: cubic. Typical habit: microscopic crystals.
Often confused with
Manganochromite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside manganochromite
Minerals reported to co-occur with manganochromite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnCr₂O₄
- Mohs hardness
- 5.5
- Density
- 4.86 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Semitransparent
- Crystal system
- Cubic
- Crystal habit
- Microscopic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- From an extension gash vein in a metamorphosed hydrothermal pyrite deposit (Nairne deposit, South Australia); in a metamorphosed iron sulfide deposit associated with submarine felsic volcanism (Sätra mine, Sweden)
Where rockhounds find manganochromite
Classic worldwide localities
- Nairne deposit, near Brukunga, 47 km east of Adelaide, South Australia
- Sätra mine, Doverstorp, Bergslagen metallic province, Sweden
Field-hunting tip
Where it forms: From an extension gash vein in a metamorphosed hydrothermal pyrite deposit (Nairne deposit, South Australia); in a metamorphosed iron sulfide deposit associated with submarine felsic volcanism (Sätra mine, Sweden). If you start seeing pyrrhotite, rutile, diopside in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify manganochromite?+
Where is manganochromite found?+
What rocks look like manganochromite?+
What minerals are found with manganochromite?+
What kind of rock does manganochromite form in?+
What is manganochromite used for?+
Find manganochromite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
