The enneahydrate MgSO4·9H2O was discovered and characterised only not long ago, even though it seems quick to produce (by cooling a solution of MgSO4 and sodium sulfate Na2SO4 in suited proportions). The heptahydrate will take its typical title "Epsom salt" from a bitter saline spring in Epsom in Surrey, England, https://dickn669ask5.jts-blog.com/profile