What was added to this glass to make it blue?
ink
lead
cobalt
magnesium
Powdered cobalt glass, called smalt, has been historically important as a pigment in painting and pottery. It is colored to a deep powder blue hue using cobalt ions derived from cobalt oxide. Cobalt aluminate can be used in a similar way, and is now more common, often known as "cobalt blue".
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Answers by country
ink
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cobalt
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answers
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