Geoscience Reference
In-Depth Information
chromium chloride (CrCl
3
) added as a coloring agent or from HCl added for
increasing the acid content in the growth solution.
Figure 7.31
shows the as-grown
crystal of Regency emerald
[150]
. The crystal size is 14
6mm
3
. The seed is
colorless but is green at the upper growth layer. The green emerald layer has a
thickness three to four times that of the seed.
The study of Biron synthetic emerald began in Western Australia during 1977
[153]
. In 1985, commercial stones were synthesized and sold through the Perth
Lapidary Center under the trade name “Biron.” Biron Mineral (Pvt) Ltd. is, at pres-
ent, known as the Emerald Pool Mining Company (Pvt) Ltd
[154]
. The growth con-
ditions remain unknown. Chlorine, chromium, and vanadium have been detected in
these crystals
[153
8
3
3
155]
. IR absorption spectrometry has revealed the presence of
H
2
O. Microscopic examination has revealed the presence of gold crystals
[155]
.
This may indicate that Biron emerald was hydrothermally synthesized in an auto-
clave lined with gold or gold alloy with chromium and vanadium used as the color-
ing agents. The crystals have a remarkably large growth sector and are transparent
Figure 7.31 As-grown crystal of Regency
emerald
[150]
.
