Buttgenbachite is a rare copper nitrate mineral typically occurring as striking deep-blue, acicular, or fibrous crystal sprays. It is closely related to connellite and is primarily found in the oxidized zones of copper-rich ore deposits, often forming crusts or tufts on matrix.
Is this buttgenbachite?
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 buttgenbachite with a known reference. Buttgenbachite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale greenish blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: blue, azure.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular.
Often confused with
Buttgenbachite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Buttgenbachite is noticeably harder (Mohs 3 vs. 1-2); streak differs, so Buttgenbachite leaves pale greenish blue, Aurichalcite leaves light blue; luster reads vitreous on Buttgenbachite and silky to pearly on Aurichalcite.
How to tell apart: Streak differs, so Buttgenbachite leaves pale greenish blue, Clinoatacamite leaves greenish white; luster reads vitreous on Buttgenbachite and adamantine to vitreous on Clinoatacamite.
Often found alongside buttgenbachite
Minerals reported to co-occur with buttgenbachite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₁₉Cl₄(NO₃)₂(OH)₃₂·2H₂O
- Mohs hardness
- 3
- Density
- 3.36-3.42 g/cm³
- Streak
- Pale greenish blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular
- Cleavage
- Perfect on {10-10}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral found in the oxidized portions of copper deposits; the nitrate may be of biological origin
Where rockhounds find buttgenbachite
Classic worldwide localities
- Mildren and Steppe claims, South Comobabi Mountains, Pima Co., in the Toughnut mine, Tombstone, and at Bisbee, Cochise Co, Arizona, USA
- Seven km north of Coaldale Junction, Esmeralda Co., Nevada, USA
- Centennial mine, near Calumet, Keweenaw Co., Michigan, USA
- Likasi, Katanga Province, Congo (Shaba Province, Zaire)
- Botallack mine, St. Just, Cornwall, England
- Great Australia mine, near Cloncurry, Queensland, Australia
Field-hunting tip
Where it forms: A rare secondary mineral found in the oxidized portions of copper deposits; the nitrate may be of biological origin. If you start seeing cuprite, likasite, gerhardtite 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 buttgenbachite on the map
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