This piece is a mineral in the middle of becoming another mineral.
Azurite is unstable at the surface. Given heat or damp air it gives up part of its structure and reorganises into malachite, which is the more stable of the two. The change works inwards from the outside, which is why altering pieces go green at the edges and stay blue at the core.
Taken far enough, the malachite ends up occupying the original azurite crystal shape completely. Collectors call that a pseudomorph, and the Moroccan workings are known for producing them.
This is also the care instruction. Heat and humidity are what drive the change, so keep it somewhere dry and stable and out of direct sun, and the blue will hold. Copper carbonates are toxic if swallowed. Dust rather than wash, keep it away from children and pets, and wash your hands after handling.
Mineral: Azurite (Cu₃(CO₃)₂(OH)₂) with malachite (Cu₂(CO₃)(OH)₂), both copper carbonates
Crystal system: Both monoclinic
Origin: Morocco
Hardness: 3.5 to 4 on the Mohs scale for both; soft and brittle, handle by the matrix
Treatment: None
Dimensions: 4.87 x 4.3 x 4.28 cm
Weight: 96.42 g
You will receive the exact piece photographed.