Page 440 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

MINERAL NAME CRYSTAL SYSTEM REFRACTIVE INDICES (Rl)
pseudomalachite monoclinic α 1.80 β 1.86 γ 1.88
sampleite orthorhombic α 1.629 β 1.677 γ 1.679
Scheele's green various compounds R I greater than 1.662
Schweinfurt green not known R I 1.7ΐ; 1.78
turquoise triclinic α 1.612 β 1.620 γ 1.648
verdigris various R I ca. 1.54-1.55 (Gettens 1965)
neutral verdigris compound R I well below 1.662
basic verdigris 3 Cu(CH 3 COO) 2 .Cu(OH) 2 .5H 2 0 One R I 1.548
one I close to 1.53
R
basic verdigris 3 Cu(CH 3 COO) 2 -[Cu(OH 2 )] 2 one R I 1.580
R
one I close to 1.560
basic verdigris 3 Cu(CH 3 COO)2-[Cu(OH) 2 ] 3 -2H 2 0 one R I 1.56
neutral copper (II) formate monoclinic α 1.414 β 1.542 γ 1.557
2
basic copper (II) formate 2Cu (HCOO) 2 · Cu (OH) 2 · H 2 O R I less than 1.662
basic copper (II) formate Cu(HCOO) 2 -Cu(OH) 2 R I less than 1.662
basic copper (II) formate Cu(HCOO) 2 -2Cu(OH) 2 R I less than 1.662

As the crystal system is not known, the formula is given in its place.
l

C O P P E R M I N E R A L S A N D C O R R O S I O N P R O D U C T S
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