Cobalt green (Rinmann’s green), green colour, is obtained by precipitating a solution of cobalt chloride and zinc chloride by carbonate of soda, washing out the precipitate, drying, and burning it. Zinc green is produced by burning zinc white with sulphate, phosphoric, or arsenic of cobalt. It is as permanent as chrome green and is used in oil and watercolour painting. Turquoise green for porcelain painting is obtained by burning a stable mixture of alumina hydrate, chromium hydroxide and carbonate of cobalt oxide.
Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909