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copperas (usually uncountable, plural copperases)
- iron(II) sulfate.
- 1843, Thomas Carlyle, Past and Present, book 2, ch. 6, Monk Samson
- […] 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;
- “Copperas” in David Barthelmy, Webmineral Mineralogy Database, 1997–.
- copperas mindat.org, Hudson Institute of Mineralogy, accessed 29 August 2016