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. Buttgenbachite leaves a pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Buttgenbachite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, deep blue.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular or fibrous crystals, often as radial sprays or crusts.
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. 2); luster reads vitreous on Buttgenbachite and pearly on Aurichalcite.
How to tell apart: Streak differs — Buttgenbachite leaves pale blue, Clinoatacamite leaves apple green.
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
- 3.37 g/cm³
- Streak
- Pale Blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular or Fibrous Crystals, Often as Radial Sprays or Crusts
- Cleavage
- Perfect On {10-10}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Copper Deposits
- Typical price
- $20-200 depending on specimen size and quality
Where rockhounds find buttgenbachite
Classic worldwide localities
- Likasi, Democratic Republic of the Congo
- Chuquicamata, Chile
- Bisbee, Arizona, USA
Field-hunting tip
Look in oxidized zones of copper deposits country — that is the host setting where buttgenbachite typically forms. If you start seeing connellite, malachite, cuprite in float, you are in the right ground. Field specimens usually show a acicular or fibrous crystals, often as radial sprays or crusts habit, so 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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