Cobaltic oxide

Cobalt black at 100x (visible light left; UV light right)

Description

A naturally occurring black powder. Cobaltic oxide is used to give a brilliant blue color glaze and enamel. Cobalt oxide was used as a blue colorant in ceramic glazes and underglazes since at least the 8th century in the Middle East. It became very popular in the 14th century when it was used for Ming Dynasty ceramics. Cobaltic oxide is not used as a black paint pigment.

Synonyms and Related Terms

cobalt black; cobalt oxide; óxido de cobalto (Esp., Port.); oxyde de cobalt (Fr.); ossido cobaltico (It.); black oxide of cobalt; cobalt blue glaze

XRD

SEM

EDS

XRF

Risks

• Skin contact may cause allergies, especially on elbows, neck and ankles.
• Chronic inhalation may cause asthma.
• Ingestion may cause vomiting, diarrhea and the sensation of hotness.

Physical and Chemical Properties

• Soluble in concentrated acids. Insoluble in water.

Composition	Co2O3 or Co3O4
CAS	1308-04-9
Melting Point	895 C (dec)
Density	4.81-5.60 g/ml

Resources and Citations

• Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)

• Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993