Aurichalcite
Aurichalcite is carbonate (zinc-copper), (Zn,Cu)₅(CO₃)₂(OH)₆. In the hand, it rates 1 to 2 on the Mohs scale, and it runs pale sky blue and seafoam green-blue. Feather-soft pastel blue tufts and lacy sprays lining rusty cavities, so delicate a brush stroke can destroy them.
The geology.
Aurichalcite carries the formula (Zn,Cu)₅(CO₃)₂(OH)₆. It belongs to the monoclinic system. Catalogues list it as carbonate (zinc-copper).
It sits at 1 to 2 on the Mohs scale. The surface reads silky to pearly. Light behaviour is translucent. Specific gravity runs 3.6 to 4.2. The streak is pale blue-green. It breaks with perfect cleavage; fragile tufts.
Feather-soft pastel blue tufts and lacy sprays lining rusty cavities, so delicate a brush stroke can destroy them.
It reaches buyers as feathery tufts in cavities, velvety crusts or lacy sprays on limonite.
The origins.
Oxidized zinc-copper deposits; notable: Mapimí (Mexico), Arizona (USA, 79 mine), Lavrion (Greece).
On value, the database notes: collector specimen; pristine tufts are mid-range.
Traditional associations.
In energy work traditions, aurichalcite has little established lore; some link its pastel blue with gentle calm.
We keep this section because people ask. It sits below the geology on purpose, and none of it describes something the stone does.
Spotting the real thing.
Feather-soft pastel blue tufts and lacy sprays lining rusty cavities, so delicate a brush stroke can destroy them.
| Looks like | How to tell them apart |
|---|---|
| Rosasite | Rosasite forms firmer rounded balls; aurichalcite forms loose feathery tufts |
| Chrysocolla | Chrysocolla is massive and crust-forming, never feathery |
| Hemimorphite | Hemimorphite crusts are harder, glassier fans |
At-home tests.
Before anyone talks you into a lab report, these are the checks worth doing yourself on aurichalcite.
| Test | What you should see |
|---|---|
| By eye | Feathery habit, far too fragile to tumble |
| Acid check | Fizzes gently in vinegar |
| By eye | Extremely soft (fingernail) |
Stop short of anything that leaves a mark. A gemologist can answer the rest without damaging the stone.
Care & handling.
At 1 to 2 on the Mohs scale this is a soft material. Keep it as a display piece, store it apart from harder stones, and skip daily-wear settings.
It breaks with perfect cleavage; fragile tufts, which is worth knowing before you set it or drop it.
Skip the ultrasonic. Lukewarm water, mild soap and a soft cloth handle routine cleaning without risk.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is (Zn,Cu)₅(CO₃)₂(OH)₆. Crystal system: Monoclinic. Specific gravity: 3.6 to 4.2. Streak: Pale blue-green. Cleavage and fracture: Perfect cleavage; fragile tufts.
How it reaches the market
Oxidized zinc-copper deposits; notable: Mapimí (Mexico), Arizona (USA, 79 mine), Lavrion (Greece).
What it gets confused with
Rosasite: Rosasite forms firmer rounded balls; aurichalcite forms loose feathery tufts. Chrysocolla: Chrysocolla is massive and crust-forming, never feathery. Hemimorphite: Hemimorphite crusts are harder, glassier fans.
What it is worth
Collector specimen; pristine tufts are mid-range.
One more thing
Its name nods to 'orichalcum', the legendary brass of Atlantis, fitting for a mineral made of zinc and copper.
An education-first guide.
We do not carry aurichalcite. This page exists because the question comes up and the honest answer is worth writing down, whether or not there is anything here to sell you.
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