Egyptian blue (EB) is a heterogeneous multi-phase blue pigment originating in Egypt ≈5000 years ago. While cuprorivaite (CaCuSi 4 O 10) is the primary chromophore, color of the powdered pigment ...

Blue sharks possess a secret hidden in their skin: a sophisticated arrangement of microscopic crystals and pigments that create their brilliant blue appearance — and may allow them to change color.