Name: Hedenbergite CaFe+2Si2O6
Type: Mineral
Class: Silicate
Subclass: Inosilicate
Particle Size: Solid
Sample No.: hedenber_1
Owner: JHU
Wavelength Range: TIR
Origin: Eureka Mine, 2nd Level, Sub-level 1, 135 N, 645E, Ducktown,Tennesse, via the Smithsonian (sample no. NMNH 119197)
Collection Date: N/A
Description: The sample was made up of three large pieces and three small fragments, weighing altogether about 28 g.  All pieces are deep green and parts of single crystals.  They display a very small amount of veining.  Surfaces of the pieces have a veneer of contamination probably the same as the veining.  There is also an extremely small amount of sulphide contamination. (Single chain Pyroxene Group) Original ASTER Spectral Library name was jhu.nicolet.mineral.silicate.inosilicate.solid.hedenb1.spectrum.txt
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 i.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
