Page 204 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

28

P L A T E 2 6 Two small penannular bronze nose ornaments
from the site of La Compañía, Ecuador, dated to about
the tenth century . E . , showing the light green, powdery
C
eruptions typical of bronze disease.
P L A T E 27 Worshipping bodhisattvas, cave 328 , Mogao
grottoes, Dunhuang, People's Republic of China, early
Tang dynasty ( 6 1 8 - 7 0 4 ) . Polychromed stucco. The statues
are covered with fine dust that blows down from the
Mingsha dunes, obscuring the sculptures and wall paint-
ings. A variety of copper-based pigments have been
identified from these caves, including malachite, synthetic
malachite, and botallackite (probably an alteration prod-
uct of the original pigment, most likely malachite).

P L A T E 2 8 Sample of basic copper-chloride green
pigment (atacamite or paratacamite) from an eighteenth-
century Japanese painting, viewed under bright-field 2 9 Α
transmitted illumination (mounted in Aroclor R I 1.662;
magnification χ 270). Freer Gallery of Art, Smithsonian
Institution (acc. no. 00.112).

P L A T E 29 Photomicrographs of atacamite natural min­
A
eral specimen: , viewed with uncrossed polars, showing
some rather pale green crystalline fragments with some
slight internal fibrous character and other fragments that
B
vary in color from very pale to darker green; and , under
crossed polars, showing subtle blue homogeneous bire­
fringence. Some fibrous directional character to these
clear particles can still be seen (both in melt-mount
R I 1.662; magnification χ 347). Collections of the British
Museum, Natural History.

29B

187