Azurite
Cu₃(CO₃)₂(OH)₂ · Monoclinic
Azurite is malachite's blue counterpart, formed in the same oxidised copper zones. It is chemically unstable over long periods and slowly converts to malachite, which is why so many specimens are half blue and half green.
Properties
- Mohs hardness
- 3.5–4
- Streak
- light blue
- Lustre
- vitreous, dull
- Colour
- A deep azure blue that darkens almost to black in massive material.
- Cleavage
- Perfect in one direction.
- Fracture
- Conchoidal
- Specific gravity
- 3.7–3.9 (water = 1)
- Magnetism
- Not magnetic
- Acid test
- Fizzes on contact
- UV
- Not fluorescent
Tests that confirm azurite
- Fizzes in dilute acid.
- Light blue streak — no other common blue mineral does this.
- Very frequently found alongside, or partly replaced by, green malachite.
What azurite gets confused with
Each of these is settled by one test. Run that test first.
Lazurite / lapis lazuli
Lapis is harder, does not fizz in acid, and usually carries gold-coloured pyrite flecks.
Chrysocolla
Chrysocolla is greener, softer, and does not effervesce.
Where it is found
Oxidised copper deposits, especially in arid regions.
Is it worth anything?
Sharp crystals are collectible and can be valuable. Keep specimens out of direct sunlight, which accelerates alteration.