copperas

• coperas

From Middle English coperas, coperose (“metallic sulfate”), from Old French coperose. Compare French couperose (“sulfate”), Medieval Latin cuprosa, Late Latin aqua cuprosa, Latin cupri rosa, "rose of copper".

copperas (usually uncountable, plural copperases)

1. iron(II) sulfate.
   • 1707, J[ohn] Mortimer, The Whole Art of Husbandry; or, The Way of Managing and Improving of Land. […], 2nd edition, London: […] J[ohn] H[umphreys] for H[enry] Mortlock […], and J[onathan] Robinson […], published 1708, →OCLC:

     It were superfluous to describe the Process of making the Aqua fortis; it shall suffice to let you know, that our common Coperas makes this Aquafortis well enough for our purpose […]

   • 1843 April, Thomas Carlyle, “ch. 6, Monk Samson”, in Past and Present, American edition, Boston, Mass.: Charles C[offin] Little and James Brown, published 1843, →OCLC, book II (The Ancient Monk):

     […] what a change has introduced itself everywhere into human affairs! How human affairs shall now circulate everywhere not healthy life-blood in them, but, as it were, a detestable copperas banker’s ink;

2. obsolete sulphate compound with one of three metals, zinc, copper or iron

• vitriol

• blue copperas
• green copperas
• yellow copperas
• white copperas

• copperas on merriam-webster.com
• David Barthelmy (1997–2024) “Copperas”, in Webmineral Mineralogy Database.
• “copperas”, in Mindat.org‎, Hudson Institute of Mineralogy, 2000–2024.