Middlebackite is a rare lead-copper carbonate chloride mineral discovered in the oxidized zones of ore deposits in South Australia. It is typically found as small, distinct blue tabular crystals and is highly sought after by advanced collectors for its rarity and crystal form.
Is this middlebackite?
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 middlebackite with a known reference. Middlebackite 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: pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Middlebackite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Cerussite is the harder of the two (Mohs 3-3.5 vs. ~2); streak differs, so Middlebackite leaves pale blue, Cerussite leaves white; luster reads vitreous on Middlebackite and adamantine, tending toward vitreous, resinous on Cerussite.
How to tell apart: Malachite is the harder of the two (Mohs 3.5-4 vs. ~2); luster reads vitreous on Middlebackite and adamantine to vitreous; silky if fibrous; dull to earthy if massive on Malachite.
How to tell apart: Streak differs, so Middlebackite leaves pale blue, Phosgenite leaves white; luster reads vitreous on Middlebackite and adamantine on Phosgenite.
Often found alongside middlebackite
Minerals reported to co-occur with middlebackite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂(C₂)O₄(OH)₂
- Mohs hardness
- ~2
- Density
- 3.64 g/cm³
- Colors
- Streak
- Pale blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals
- Cleavage
- One perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A supergene mineral in a weathered Precambrian manganiferous sedimentary iron ore deposit
Where rockhounds find middlebackite
Classic worldwide localities
- Middleback Range, South Australia
Field-hunting tip
Where it forms: A supergene mineral in a weathered Precambrian manganiferous sedimentary iron ore deposit. If you start seeing atacamite, mottramite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find middlebackite on the map
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