A blue pigment obtained by roasting cobalt ore(noun)
A cobalt blue colour, like that of the pigment(noun)
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Use "zaffre" in a sentence
"Ores found in Saxony and Connecticut -- combined with arsenic, zaffre and smalt -- composition and use of the latter -- use of cobalt in colouring glass and pottery -- nitrate of cobalt a fine sympathetic ink."
"The Saxon mines have till very lately almost exclusively supplied the rest of Europe with cobalt, or rather with its preparations, zaffre and smalt, for the exportation of the ore itself is there a capital crime."