Copperas
/ˈkɒp.ər.əs/noun
A greenish or bluish-green crystalline sulfate, especially ferrous sulfate, formerly used in dyeing and ink-making.
Did you know?Copperas is historically tied to the vitriol tradition of alchemy, where crystalline sulfates were prized, named, and handled as powerful substances long before modern chemistry.
Etymological Timeline
Late Latin
LL
copperosa
“A copper-colored or copper-like substance; later associated with vitriolic salts”
Old French
OF
couperose
“Copper rust; a copper-colored mineral or corrosive substance”
Middle English
ME
coperose
“Copperas; vitriol used in dyeing and ink-making”
16th Century
English
copperas
“Ferrous sulfate or related vitriolic salts used in trade and crafts”
Modern English
English
copperas
“A historical name for ferrous sulfate and similar sulfate salts”
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