Name: Topaz Al2SiO4(F,OH)2
Type: Mineral
Class: Silicate
Subclass: Nesosilicate
Particle Size: Coarse
Sample No.: topaz_2
Owner: JHU
Wavelength Range: TIR
Origin: Ouro Preto, Brazil via Don Hoover, USGS
Collection Date: N/A
Description: The sample consisted of several orange-colored, rounded (tumbled) grains, each about 1 cm in diameter.  Under the microscope, the sample appeared to be pure topaz with abundant fluid inclusions. Particle size was 75 - 250  Micrometers.(Isolated tetrahedra) Original ASTER Spectral Library name was jhu.nicolet.mineral.silicate.nesosilicate.coarse.topaz2.spectrum.txt
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
