Gamagarite is an extremely rare barium vanadium mineral found primarily in the iron-manganese deposits of the Postmasburg area. It typically occurs as small, dark brown to black tabular crystals or granular crusts, often associated with other rare manganese minerals.
Is this gamagarite?
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 gamagarite with a known reference. Gamagarite 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: reddish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: dark brown, brownish black, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, granular aggregates.
Often confused with
Gamagarite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Gamagarite is noticeably harder (Mohs 4.5-5 vs. 2.5-3); streak differs, so Gamagarite leaves reddish brown, Vanadinite leaves white to pale red or pale yellow; luster reads adamantine on Gamagarite and subresinous to subadamantine on Vanadinite.
How to tell apart: Gamagarite is noticeably harder (Mohs 4.5-5 vs. 3-3.5); streak differs, so Gamagarite leaves reddish brown, Descloizite leaves orange to brownish red; luster reads adamantine on Gamagarite and greasy on Descloizite.
Often found alongside gamagarite
Minerals reported to co-occur with gamagarite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba₂Fe(VO₄)₂(OH)
- Mohs hardness
- 4.5-5
- Density
- 4.62-4.68 g/cm³
- Streak
- Reddish brown
- Luster
- Adamantine
- Transparency
- Transparent in thin fragments
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals, granular aggregates
- Cleavage
- {001} and {100}, distinct; {101} difficult, indices probable
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Very rare, in banded manganese ore replacing shale (Gloucester Farm, South Africa); in veinlets cutting manganese ore (Molinello mine, Italy)
Where rockhounds find gamagarite
Classic worldwide localities
- Gamagara Ridge, on Gloucester Farm, about 27 km north of Postmasburg, Cape Province, South Africa
- Molinello manganese mine, near Chiavari, Val Graveglia, Liguria, Italy
Field-hunting tip
Where it forms: Very rare, in banded manganese ore replacing shale (Gloucester Farm, South Africa); in veinlets cutting manganese ore (Molinello mine, Italy). If you start seeing bixbyite, hematite, ephesite in float, you are in the right ground. Typical habit: tabular crystals, granular aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gamagarite?+
Where is gamagarite found?+
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What rocks look like gamagarite?+
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Find gamagarite on the map
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