Bederite is a very rare manganese-rich member of the garnet group primarily identified from specific manganese deposits in South Africa. It typically presents as small, yellowish to brownish-yellow dodecahedral crystals that require analytical verification to distinguish from other similar garnets. Collectors value it highly due to its scarcity and distinct chemical composition compared to more common garnet species.
Is this bederite?
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 bederite with a known reference. Bederite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark olive-green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: very dark brown, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive, nodular.
Often confused with
Bederite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Andradite is the harder of the two (Mohs 6.5-7 vs. 5); streak differs, so Bederite leaves dark olive-green, Andradite leaves white; luster reads vitreous on Bederite and adamantine to resinous, dull on Andradite.
How to tell apart: Spessartine is the harder of the two (Mohs 7-7.5 vs. 5); streak differs, so Bederite leaves dark olive-green, Spessartine leaves white.
How to tell apart: Goldmanite is the harder of the two (Mohs 7 vs. 5); streak differs, so Bederite leaves dark olive-green, Goldmanite leaves white.
Often found alongside bederite
Minerals reported to co-occur with bederite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Mn₄Fe₂(PO₄)₆·2H₂O
- Mohs hardness
- 5
- Density
- 3.48 g/cm³
- Colors
- Very dark brownBlack
- Streak
- Dark olive-green
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Massive, nodular
- Cleavage
- {100}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of rare occurrence in a complex granite pegmatite in mica schist
Where rockhounds find bederite
Classic worldwide localities
- El Peñón pegmatite, El Quemado district, Nevados de Palermo, Salta Province, Argentina
Field-hunting tip
Where it forms: Of rare occurrence in a complex granite pegmatite in mica schist. If you start seeing muscovite, quartz, potassic feldspar in float, you are in the right ground. Typical habit: massive, nodular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bederite?+
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What rocks look like bederite?+
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Find bederite on the map
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