Bonaccordite is an extremely rare borate mineral known primarily from the Bon Accord nickel deposit in South Africa. It typically occurs as dark brown to black acicular needles or fibrous aggregates, often intergrown with other nickel-bearing minerals. Due to its limited occurrence, it is highly sought after by advanced systematic mineral collectors.
Is this bonaccordite?
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 bonaccordite with a known reference. Bonaccordite sits at Mohs 7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: reddish brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals, fibrous aggregates.
Often confused with
Bonaccordite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Bonaccordite is noticeably harder (Mohs 7 vs. 5-5.5); streak differs, so Bonaccordite leaves brown, Ludwigite leaves black to greenish black; luster reads vitreous to adamantine on Bonaccordite and submetallic on Ludwigite.
How to tell apart: Bonaccordite is noticeably harder (Mohs 7 vs. 5); streak differs, so Bonaccordite leaves brown, Vonsenite leaves brownish black; luster reads vitreous to adamantine on Bonaccordite and metallic to submetallic, silky if fibrous on Vonsenite.
Often found alongside bonaccordite
Minerals reported to co-occur with bonaccordite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ni₂FeBO₅
- Mohs hardness
- 7
- Density
- 5.17 g/cm³
- Colors
- Streak
- Brown
- Luster
- Vitreous to adamantine
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular crystals, fibrous aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a small tabular body of nickeliferous serpentinite, probably a contact deposit, along the junction of quartzite and an ultramafic intrusive
Where rockhounds find bonaccordite
Classic worldwide localities
- Found three km west of the Scotia talc mine, Bon Accord area, Barberton, Transvaal, South Africa
Field-hunting tip
Where it forms: In a small tabular body of nickeliferous serpentinite, probably a contact deposit, along the junction of quartzite and an ultramafic intrusive. If you start seeing trevorite, liebenbergite, nepouite in float, you are in the right ground. Typical habit: acicular crystals, fibrous aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
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Find bonaccordite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
