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. Philipsbornite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Philipsbornite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, pale yellow, yellowish-green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: small rhombohedral crystals, sometimes forming crusts.
Often confused with
Philipsbornite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Philipsbornite leaves white, Beudantite leaves yellow.
How to tell apart: Streak differs — Philipsbornite leaves white, Segnitite leaves yellowish; luster reads vitreous on Philipsbornite and resinous on Segnitite.
How to tell apart: Streak differs — 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)(SO₄)(OH)₆
- Mohs hardness
- 4.5
- Density
- 4.3-4.5 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Small Rhombohedral Crystals, Sometimes Forming Crusts
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Hydrothermal Base-metal Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find philipsbornite
Classic worldwide localities
- Tsumeb Mine, Namibia
- Cerro Gordo, California, USA
- Mapimi, Mexico
Field-hunting tip
Look in oxidized zones of hydrothermal base-metal deposits country — that is the host setting where philipsbornite typically forms. If you start seeing tsumcorite, mimetite, smithsonite in float, you are in the right ground. Field specimens usually show a small rhombohedral crystals, sometimes forming crusts habit, so 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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