Philipsbornite is a rare arsenate mineral belonging to the beudantite group, typically found as tiny rhombohedral crystals in the oxidation zones of lead-bearing deposits. It is most famous for its occurrences at the Tsumeb mine in Namibia, where it presents as delicate, pale yellowish or white clusters.
Is this philipsbornite?
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 philipsbornite with a known reference. Philipsbornite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless, gray green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: earthy, massive.
Often confused with
Philipsbornite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Philipsbornite leaves white, Beudantite leaves grayish yellow to green.
How to tell apart: Streak differs, so Philipsbornite leaves white, Segnitite leaves pale yellow.
How to tell apart: Streak differs, so Philipsbornite leaves white, Corkite leaves yellow.
Often found alongside philipsbornite
Minerals reported to co-occur with philipsbornite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbAl₃(AsO₄)(AsO₃OH)(OH)₆
- Mohs hardness
- 4.5
- Density
- 4.33 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent to transparent
- Crystal system
- Trigonal
- Crystal habit
- Earthy, massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of hydrothermal polymetallic mineral deposits
Where rockhounds find philipsbornite
Classic worldwide localities
- Dundas district, Tasmania, and in the Anticline and Bali Lo prospects, 11 km west-southwest of Ashburton Downs homestead, Capricorn Range, Western Australia
- Tsumeb, Namibia
- Cínovec (Zinnwald), and at Moldava, 20 km northwest of Teplice, Czech Republic
- Clara mine, near Oberwolfach, in the Michael mine, Weiler, near Lahr, and at Neubulach, Black Forest, Germany
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of hydrothermal polymetallic mineral deposits. If you start seeing crocoite, hidalgoite, gorceixite in float, you are in the right ground. Typical habit: earthy, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find philipsbornite on the map
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