Andreas
Ertl, Gerald Giester
Institut
für Mineralogie und Kristallographie,
Geozentrum, Universität Wien, Althanstrasse 14, 1090 Vienna, Austria
Thomas Ludwig, Hans-Peter Meyer
Institut
für Geowissenschaften, Universität Heidelberg,
Im Neuenheimer Feld 236, 69120 Heidelberg, Germany
George
R. Rossman
Division
of Geological and Planetary Sciences, California Institute of
Technology,
Pasadena,
California 91125, USA
ABSTRACT
Synthetic
Al- and B-rich
tourmaline crystals described by
X(Na0.7˙0.3) Y(Al2.5Li0.4Fe2+0.1)
ZAl6 (BO3)3
[Si5.2B0.5Al0.3O18]
V[(OH)2.9O0.1]
W[O0.9(OH)0.1],
with a = 15.765(1), c
= 7.083(1) Å,
X(Na0.7˙0.3) Y(Al2.5Li0.5)
ZAl6
(BO3)3 [Si4.8B0.9Al0.3O18]
V(OH)3 W[(OH)0.5O0.5],
with a = 15.746(1), c
= 7.075(1) Å, and
X(Na0.6Ca0.1˙0.3) Y(Al2.3Li0.5Fe0.2)
ZAl6 (BO3)3
[Si4.7B1.2Al0.2O18]
V(OH)3 W[(OH)0.9O0.1],
with a = 15.723(1), c
= 7.068(1) Å.
The small <T-O>
distances, down to 1.599 Å, reflect relatively high amounts of [4]B
(up to ~1.2 apfu; refinements with R
= ~2%). All these samples also contain significant amounts of [4]Al
(~0.2 apfu). A pronounced
negative correlation (r2
= 1.00; only three data points) between temperature during
crystal growth (at a constant pressure) and [4]B
(from refinement)
in these synthetic olenites was found.
Synthetic B-rich olenite at top of dark seed-crystal in two polarizations
Birefringence of the synthetic B-rich overgrowth - crossed polarizers
last revised: 1-Jun-2012