Galaxite is a rare member of the spinel group, typically found as opaque, black, octahedral crystals. It is most famous for its occurrence in the manganese-rich deposits of Bald Knob, where it often forms alongside other manganese-bearing minerals.
Is this galaxite?
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 galaxite with a known reference. Galaxite sits at Mohs 7.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Galaxite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Galaxite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black, reddish-brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals, massive, granular.
Often confused with
Galaxite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Galaxite is noticeably harder (Mohs 7.5 vs. 5.5-6.5); luster reads submetallic on Galaxite and metallic on Magnetite.
How to tell apart: Galaxite is noticeably harder (Mohs 7.5 vs. 5.5); streak differs — Galaxite leaves black, Chromite leaves dark brown.
How to tell apart: Galaxite is noticeably harder (Mohs 7.5 vs. 5.5-6.5); streak differs — Galaxite leaves black, Franklinite leaves reddish-brown; luster reads submetallic on Galaxite and metallic on Franklinite.
Often found alongside galaxite
Minerals reported to co-occur with galaxite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnAl₂O₄
- Mohs hardness
- 7.5
- Density
- 4.2-4.5 g/cm³
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Octahedral Crystals, Massive, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Manganese Deposits
- Typical price
- $20-150 for small specimens
Where rockhounds find galaxite
Classic worldwide localities
- Bald Knob, North Carolina, USA
- Långban, Sweden
- Jacupiranga, Brazil
Field-hunting tip
Look in metamorphosed manganese deposits country — that is the host setting where galaxite typically forms. If you start seeing spessartine, rhodonite, tephroite in float, you are in the right ground. Field specimens usually show a octahedral crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find galaxite on the map
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