Mineral:  Topaz Al2SiO4(F,OH)2

Sample No.:  topaz.2

XRD Analysis:  Pure topaz.

Chemistry:  Microprobe analysis by Lou Walter and volatile analysis 
by C. S. Papp, J. D. Sharkey, and K. J. Curry, USGS Branch of Analytical 
Chemistry, Denver.  Ten microprobe analyses indicate homogeneity 
within and between grains.  Composition agrees with that of a topaz 
that is OH-rich, which is consistent with the intensity of the OH bands 
in the spectrum.  (Note that the spectrum has a strong CO2 band at 
4.3 micrometers typically seen in the more OH-rich samples.  Because 
F-rich topaz is orthorhombic and OH-rich triclinic, there are also 
significant differences in the reststrahlen bands between topaz 
samples.) Average of 10 analyses:

SiO2	36.03
Al2O3	61.70
FeO	0.04
MgO	0.12
CaO	<0.02
K2O	<0.02
Na2O	<0.17
TiO2	<0.02
MnO	<0.02
P2O5	<0.06
H2O	1.67
CO2	<0.01
F	0.04
	_____
Total	99.92
