Cobalt blue

Cobalt blue
 
A sample of a commercial cobalt blue pigment
About these coordinates     Color coordinates
Hex triplet#0047AB
sRGBB (r, g, b)(0, 71, 171)
HSV (h, s, v)(215°, 100%, 67%)
CIELChuv (L, C, h)(33, 82, 259°)
Source[Unsourced]
ISCC–NBS descriptorVivid blue
B: Normalized to [0–255] (byte)
Cobalt blue
Identifiers
3D model (JSmol)
ChemSpider
EC Number
  • 310-193-6
  • InChI=1S/2Al.Co.4O/q;;+2;;;2*-1
    Key: BVTIIQXILLBFIK-UHFFFAOYSA-N
  • [O-][Al]=O.[O-][Al]=O.[Co+2]
Properties
Al2CoO4
Molar mass 176.892 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Cobalt blue is a blue pigment made by sintering cobalt(II) oxide with aluminum(III) oxide (alumina) at 1200 °C. Chemically, cobalt blue pigment is cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. Cobalt blue is lighter and less intense than the (iron-cyanide based) pigment Prussian blue. It is extremely stable and historically has been used as a coloring agent in ceramics (especially Chinese porcelain), jewelry, and paint. Transparent glasses are tinted with the silica-based cobalt pigment "smalt".