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. Streak: red-brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: black, brown red.
- 5Look at form & habitCrystal system: cubic. Typical habit: 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); streak differs, so Galaxite leaves red-brown, Magnetite leaves black; luster reads vitreous on Galaxite and metallic to submetallic, may be dull on Magnetite.
How to tell apart: Galaxite is noticeably harder (Mohs 7.5 vs. 5.5); streak differs, so Galaxite leaves red-brown, Chromite leaves brown; luster reads vitreous on Galaxite and metallic to submetallic on Chromite.
How to tell apart: Galaxite is noticeably harder (Mohs 7.5 vs. ~6); streak differs, so Galaxite leaves red-brown, Franklinite leaves reddish brown to black; luster reads vitreous on Galaxite and metallic to semimetallic; may be dull 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
- 4.234 g/cm³
- Streak
- Red-brown
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Granular
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In carbonate-rich, silica-undersaturated parts of metamorphosed manganese deposits
Where rockhounds find galaxite
Classic worldwide localities
- Occurs near Bald Knob, Alleghany Co., North Carolina, USA
- Brattfors and Jakobsberg mines, Värmland, Sweden
- Found near Bonneval-sur-Arc, Haute-Savoie, France
- Found at the Noda-Tamagawa mine and Hijikuzu, Iwate Prefecture, Japan
- Oashi mine, Tochigi Prefecture, Japan
- Taguchi mine, Aichi Prefecture, Japan
Field-hunting tip
Where it forms: In carbonate-rich, silica-undersaturated parts of metamorphosed manganese deposits. If you start seeing alleghanyite, rhodonite, sonolite in float, you are in the right ground. Typical habit: granular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find galaxite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
