[science2000]

Some Cobalt salts are swich-hitters, sometimes they're blue and other times pink.
For example, after producing some cobalt carbonate, the precipitate was a mix of blue and pink, making a purplish slurry. Does anyone know explanation for this random color difference?

[Borek]

Some Cobalt salts are swich-hitters, sometimes they're blue and other times pink.

Depending on air humidity number of water particle surrounding hydrated cobalt cation changes, changing color of the salt.