Whelanite is an exceptionally rare secondary copper-lead silicate mineral known primarily from the 79 Mine in Arizona. It typically occurs as delicate, radiating clusters of blue to blue-green acicular crystals associated with other oxidized lead and copper minerals.
Is this whelanite?
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 whelanite with a known reference. Whelanite 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. Streak: pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pale blue.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals, fibrous bundles, radiating aggregates.
Often confused with
Whelanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Planerite is the harder of the two (Mohs 5 vs. ~2.5); streak differs, so Whelanite leaves pale blue, Planerite leaves blue white; luster reads vitreous on Whelanite and dull, chalky to earthy on Planerite.
How to tell apart: Streak differs, so Whelanite leaves pale blue, Chrysocolla leaves white when pure.
Often found alongside whelanite
Minerals reported to co-occur with whelanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂Ca₆[Si₆O₁₇(OH)](CO₃)(OH)₃(H₂O)₂
- Mohs hardness
- ~2.5
- Density
- 2.74 g/cm³
- Colors
- Streak
- Pale blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular crystals, fibrous bundles, radiating aggregates
- Cleavage
- Perfect on {001}; good on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a copper-rich, diopside-garnet-magnetite contact metamorphic rock (skarn)
Where rockhounds find whelanite
Classic worldwide localities
- Bawana mine, Rocky mining district, 5 miles NW of Milford, Beaver County, Utah, USA
- Christmas mine, Pinal County, Arizona, USA
- Bird Springs in the Nelson Range, Inyo County, California, USA
- Commercial quarry, Crestmore, Sky Blue Hill, Riverside County, California, USA
Field-hunting tip
Where it forms: In a copper-rich, diopside-garnet-magnetite contact metamorphic rock (skarn). If you start seeing thaumasite, stringhamite, kinoite in float, you are in the right ground. Typical habit: acicular crystals, fibrous bundles, radiating aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
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Find whelanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
