Copperas or blue stone, kainite and superphosphate are sometimes used for the same purpose.    From Wordnik.com.  [The First Book of Farming] Reference

For over a century, rock phosphate and kainite -- a soft, readily soluble naturally occurring rock rich in potassium, magnesium and sulfur -- have been ground and used as fertilizer.    From Wordnik.com.  [Organic Gardener's Composting] Reference

To the substances used for treating brewing liquors already mentioned we may add kainite, a naturally deposited composite salt containing potassium and magnesium sulphates and magnesium chloride.    From Wordnik.com.  [Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria"] Reference

K - a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite.    From Wordnik.com.  [Word of the Day] Reference

Ph. D., said, "Tezampanel and its oral prodrug NGX426 are the first glutamate receptor antagonists to be tested in human pain trials with combined binding activity at the AMPA and kainite receptor subtypes.    From Wordnik.com. Reference

(hydrous potassium-magnesium chloride), kieserite (hydrous magnesium sulphate), sylvite (potassium chloride), kainite (a hydrous double salt of potassium chloride and magnesium sulphate), and common salt (sodium chloride).    From Wordnik.com.  [The Economic Aspect of Geology] Reference