Mineral:  Hedenbergite CaFe+2Si2O6

Sample No.: hedenber.1

Under the microscope this appears to be largely pure hedenbergite 
with a rather small (<1%) degree of alteration.  A few large, high-
birefringent carbonate (?) grains are present.

XRD Analysis:  XRD indicates pure hedenbergite, with no sign of 
exsolved orthopyroxene or carbonate.  (The carbonate does show up, 
however, in the infrared spectrum, especially of the finest particle-
size range, showing the infrared more sensitive than XRD for 
detection of carbonate).

Chemistry:  Microprobe analysis showed slight heterogeneity within 
and between grains Ņi.e., alumina varies between 0.5 and 1.5% with 
no concomitant variation of the other oxides measured. Average of 9 
analyses:

SiO2	53.36
Al2O3	0.87
FeO	6.45
MgO	14.35
CaO	24.53
K2O	0.03
Na2O	0.48
TiO2	0.04
MnO	0.73
	_____
Total 	100.84
