Bobfergusonite is a rare phosphate mineral typically found in phosphate nodules within iron-rich sedimentary formations. It is characterized by its distinct reddish-brown color and vitreous luster, often appearing as granular masses in mineral assemblages alongside other phosphates like ludlamite and vivianite.
Is this bobfergusonite?
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 bobfergusonite with a known reference. Bobfergusonite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bobfergusonite leaves a yellowish brown streak.
- 3Read the lusterHold the specimen under a strong light. Bobfergusonite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: reddish brown, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular to massive.
Often confused with
Bobfergusonite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside bobfergusonite
Minerals reported to co-occur with bobfergusonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Mn²⁺₅Fe³⁺Al(PO₄)₆
- Mohs hardness
- 4
- Density
- 3.55 g/cm³
- Colors
- Streak
- Yellowish Brown
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Granular to Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-rich Nodules in Iron-formation
- Typical price
- $50-300 per specimen
Where rockhounds find bobfergusonite
Classic worldwide localities
- Big Fish River, Yukon, Canada
- Rapid Creek, Yukon, Canada
Field-hunting tip
Look in phosphate-rich nodules in iron-formation country — that is the host setting where bobfergusonite typically forms. If you start seeing quartz, siderite, ludlamite in float, you are in the right ground. Field specimens usually show a granular to massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find bobfergusonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
