Philipsburgite is a rare secondary copper arsenate mineral typically found as vibrant green crusts or small crystalline aggregates. It is prized by collectors for its brilliant color and is most famously associated with the Black Pine Mine in Montana, where it often coats other copper minerals.
Is this philipsburgite?
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 philipsburgite with a known reference. Philipsburgite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: emerald green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: botryoidal crusts, aggregates, occasionally tiny prismatic crystals.
Often confused with
Philipsburgite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Philipsburgite leaves pale green, Austinite leaves white; luster reads vitreous on Philipsburgite and subadamantine to silky in aggregates on Austinite.
How to tell apart: Streak differs, so Philipsburgite leaves pale green, Conichalcite leaves green.
How to tell apart: Streak differs, so Philipsburgite leaves pale green, Olivenite leaves olive-green to brown; luster reads vitreous on Philipsburgite and adamantine to vitreous, pearly to silky if fibrous on Olivenite.
Often found alongside philipsburgite
Minerals reported to co-occur with philipsburgite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Cu,Zn)₆(AsO₄,PO₄)₂(OH)₆·H₂O
- Mohs hardness
- 3-4
- Density
- 4.07 g/cm³
- Colors
- Streak
- Pale green
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Botryoidal crusts, aggregates, occasionally tiny prismatic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of hydrothermal base-metal deposits
Where rockhounds find philipsburgite
Classic worldwide localities
- Black Pine mine, about 14.5 km northwest of Philipsburg, Granite Co., Montana, USA
- Gold Hill mine, Tooele Co., and in the Centennial Eureka mine, Tintic district, Juab Co., Utah, USA
- Potts Gill mine and the Low Pike vein, Caldbeck Fells, Cumbria, England
- Wheal Carpenter, Gwinear, and the Penberthy Croft mine, St. Hilary, Cornwall, England
- Clara mine, near Oberwolfach, Black Forest, and from Schwarzenberg, Saxony, Germany
- Brixlegg, Tirol, Austria
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of hydrothermal base-metal deposits. If you start seeing bayldonite, chrysocolla, mimetite in float, you are in the right ground. Typical habit: botryoidal crusts, aggregates, occasionally tiny prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find philipsburgite on the map
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