This print is part of a series commemorating the 150th (2019) year of the periodic table of elements.
 
First recorded by the Greeks in 5 BCE in one of its naturally occurring forms Alum. Alum means bitter in latin and it is a type of salt that looks like crystal but behave in some physical ways as a metall. Roman philosopher ,Pliny the Elder, describes it in detail in his first century publication Natural History.