Identification guide · Minerals
How to Identify Aurichalcite
Aurichalcite forms fine, hair-like or feathery crystal sprays in pale blue-green to greenish-blue shades, with a silky to pearly luster. It is very soft, around 1 to 2 on the Mohs scale, easily marked with a fingernail, and leaves a pale blue-green streak. There is no useful cleavage to observe given the crystal size, but the acicular, tufted habit is diagnostic. It can be confused with smithsonite or malachite, though both are noticeably harder.
Aurichalcite identification checklist
| Color | Pale green, Blue-green, Sky blue | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Silky, pearly | Compare a fresh surface with glass and metal; this luster is softer than either. |
| Transparency | Translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 1–2 | A fingernail (Mohs 2.5) scratches it easily. |
| Streak | Pale blue-green | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect, one direction (basal) | |
| Fracture | Sectile | |
| Specific gravity | 3.6–3.9 | Heavier than it looks (specific gravity about 3.75). |
| Crystal system | Monoclinic |
Extra tests for Aurichalcite
Acid test. Fizzes in vinegar or dilute hydrochloric acid because of its carbonate content.
Aurichalcite look-alikes and how to tell them apart
Calcite is harder (Mohs 3) than Aurichalcite (Mohs 1–2), so Calcite will scratch Aurichalcite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Aurichalcite vs Calcite →
Amber is harder (Mohs 2.5) than Aurichalcite (Mohs 1–2), so Amber will scratch Aurichalcite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Aurichalcite vs Amber →
Chrysocolla is harder (Mohs 2.5) than Aurichalcite (Mohs 1–2), so Chrysocolla will scratch Aurichalcite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Aurichalcite vs Chrysocolla →
Both sit near Mohs 1–2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Aurichalcite identification FAQ
How can you tell if a rock is Aurichalcite?
Check the color (pale green, blue-green, and sky blue), the silky, pearly luster, a Mohs hardness of 1–2 and a pale blue-green streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Aurichalcite?
Aurichalcite has a Mohs hardness of 1–2. A fingernail (Mohs 2.5) scratches it easily.
What is the difference between Aurichalcite and Calcite?
Aurichalcite (Mohs 1–2, silky, pearly luster) and Calcite (Mohs 3, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Aurichalcite vs Calcite comparison for a side-by-side table.
Is Aurichalcite worth anything?
Entry-level Aurichalcite specimens sell for around $2, typical collector pieces about $20, and premium examples $150 or more depending on size, quality and locality.
What color is Aurichalcite?
Aurichalcite is most often pale green, blue-green, and sky blue. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
