Nissonite is a rare copper-magnesium phosphate that typically forms as delicate, thin blue-green platy crystals or crusts in oxidized zones of copper deposits. Collectors should look for it as small, fragile coatings within vugs alongside other secondary copper minerals. It is highly valued for its distinct color and rarity, usually appearing as microscopic specimens.
Is this nissonite?
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 nissonite with a known reference. Nissonite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Nissonite leaves a pale blue-green streak.
- 3Read the lusterHold the specimen under a strong light. Nissonite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue-green, pale green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, crusts, radial aggregates.
Often confused with
Nissonite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Nissonite leaves pale blue-green, Vauquelinite leaves greenish-yellow; luster reads vitreous on Nissonite and resinous to adamantine on Vauquelinite.
How to tell apart: Streak differs — Nissonite leaves pale blue-green, Torbernite leaves pale green.
Often found alongside nissonite
Minerals reported to co-occur with nissonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuMg(PO₄)(OH)·2.5H₂O
- Mohs hardness
- 2.5
- Density
- 3.31 g/cm³
- Colors
- Streak
- Pale Blue-green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Crusts, Radial Aggregates
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Copper-bearing Hydrothermal Deposits
- Typical price
- $20-150 for micro-specimens
Where rockhounds find nissonite
Classic worldwide localities
- Foster mine, California, USA
- Gold Hill, Utah, USA
- Reocin mine, Spain
Field-hunting tip
Look in oxidized copper-bearing hydrothermal deposits country — that is the host setting where nissonite typically forms. If you start seeing malachite, azurite, chrysocolla in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find nissonite on the map
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