Verdigris (/ˈvɜːrdɪɡriː(s)/)[1] is a common name for any of a variety of somewhat toxic[2][3][4]coppersalts of acetic acid, which range in colour from green to a bluish-green depending on their chemical composition.[5]: 132 Once used as a medicine[6][7] and pharmaceutical preparation,[8]: 176 [9] verdigris occurs naturally, creating a patina on copper, bronze, and brass, and is the main component of a historic green pigment used for artistic purposes from antiquity until the late 20th century, including in easel painting, polychromatic sculptures, and illumination of maps.[9]: 414–423 [10] However, due to its instability, its popularity declined as other green pigments became readily available.[8]: 171 The instability of its appearance stems from its hydration level and basicity, which change as the pigment interacts with other materials over time.[11]: 637
^"Its pronunciation in English is still unsettled" (Fowler's Dictionary of Modern English Usage (4 ed.) edited by: Jeremy Butterfield). The pronunciation /-ɡriːs/ is the first one given by Merriam-Webster's dictionary, but /-ɡriː/ is first in the Oxford Dictionary of English (3 ed.) (2015).
^H. Kühn, Verdigris and Copper Resinate, in Artists' Pigments. A Handbook of Their History and Characteristics, Vol. 2: A. Roy (Ed.) Oxford University Press 1993, p. 131 – 158
^Paris, John Ayrton (1831). Pharmacologia. New York: W. E. Dean. The rust of the spear of Telephus, mentioned in Homer as a cure for the wounds which that weapon inflicted, was probably Verdegris, and led to the discovery of its use as a surgical application