Page 202 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

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P L A T E 22 Photomicrograph of a sample from the
reverse of a Roman bronze, Victory with Cornucopia
(see P L A T E 74), showing fibrous malachite when
viewed under crossed polars (melt-mount R I 1.662).
The morphology of these crystals is very similar to
that of the malachite crystals shown in P L A T E 21,
which could provide evidence that both objects were
taken from the same burial deposit (magnification
x75o). Cleveland Museum of Art, Leonard C. Hanna,
Jr. Fund (1984.25).
P L A T E 23 Two photomicrographs of a mounted
sample of azurite crystals: , plane polarized view;
A
B
and , view under polars crossed at 0°, showing typ­
8
ical birefringence. Azurite usually appears as a clear,
pale blue color in crystalline fragments, and the par­
ticles tend to show strong pleochroism. Second-order
colors are often seen, and the extinction is distinct 25B
(magnification χ 347).
P L A T E 24 Photomicrograph of spherical particles
of synthetic malachite (green verditer), viewed under
crossed polars. Some particles have the dark cen­
ter and slightly radiating structure characteristic of
synthetic malachite (melt-mount R I 1.662; magnifi­
cation X347) .
P L A T E 25 Photomicrographs of a sample of blue
verditer: , viewed with polars crossed at 85°;
A
B, viewed under bright-field illumination, showing
pale blue-green particles with some spheroidal
character; and c, viewed with crossed polars, show­
ing typical fine-grained structure of the particles
with some growth features radiating toward the
center (all in melt-mount R I 1.662, magnification
X347) . Samples produced by Peter Mactaggart.

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