Grandviewite is a rare copper-aluminum chloride hydroxide mineral found primarily in oxidized copper ore zones. It typically forms as delicate, pale green to white micaceous or platy aggregates, often requiring magnification for clear identification.
Is this grandviewite?
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 grandviewite with a known reference. Grandviewite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: very pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: turquoise blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular.
Often confused with
Grandviewite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Connellite is the harder of the two (Mohs 3 vs. 2); streak differs, so Grandviewite leaves very pale blue, Connellite leaves pale greenish blue.
How to tell apart: Paratacamite is the harder of the two (Mohs 3 vs. 2); streak differs, so Grandviewite leaves very pale blue, Paratacamite leaves green.
Often found alongside grandviewite
Minerals reported to co-occur with grandviewite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₃Al₂(SO₄)(OH)₁₀·H₂O
- Mohs hardness
- 2
- Density
- 2.81 g/cm³
- Colors
- Turquoise blue
- Streak
- Very pale blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular
- Cleavage
- Perfect on {100} or {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral formed by the oxidation of Cu-bearing sulfides
Where rockhounds find grandviewite
Classic worldwide localities
- Grandview mine (also known as the Last Chance mine), at Cape Royal, Horseshoe Mesa, Grand Canyon National Park, Coconino County, Arizona, USA (type locality)
Field-hunting tip
Where it forms: A secondary mineral formed by the oxidation of Cu-bearing sulfides. If you start seeing chalcoalumite, cyanotrichite, carbonatecyanotrichite in float, you are in the right ground. Typical habit: acicular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find grandviewite on the map
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