Mineral:  Anhydrite CaSO4

Sample No.: anhydr.1

XRD Analysis:  XRD shows anhydrite with some gypsum present, but 
the IR spectrum is most closely that of anhydrite (note doublet at 
16.6 micrometers typical of anhydrite and lack of structural water 
doublet typical of gypsum at 2.8 micrometers). However, some water 
is clearly present.

Chemistry:  Volatile analysis by C. S. Papp, J. D. Sharkey, and K. J. 
Curry, and XRF analysis of the non-volatiles by J. Taggare, A. Bartel, 
and D. Diems, USGS Branch of Analytical Chemistry, Denver, showed 
this to be substantially anhydrite:

SiO2	0.10
Al2O3	<0.10
FeTO3	<0.04
MgO	0.20
CaO	40.70
K2O	<0.02
Na2O	<0.15
SO3 	60.67
TiO2	<0.02
P2O5	<0.05
MnO	<0.02
H2O	0.76
	_____
Total	102.83
