Calculations on Dr. Rossman's electron microprobe data by Dr. Don Hoover:

“There were three analyses, I assume from the same sample, and they all gave very similar results.  The Locock, 2008 program was used to obtain end members, which I find a bit better, in terms of matching measured properties. The results follow in percent: 

 1. Pyr67.95Alm12.27Sps11.04Gro4.61   plus Gol0.42Uva0.30      remainder 3.41 

  2. Pyr68.51Alm12.36Sps10.90Gro4.58   plus Gol0.44Uva0.36& NaTi garnet 0.07        remainder   2.77 

  3. Pyr68.94Alm12.37Sos10.85Gro4.68   plus  Gol0.44Uva0.30& NaTi garnet 0.08      remainder     2.34 

 For all three analyses there was neither charge balance nor were ideal proportions found, which is common, but does give an idea quality of analyses. 

 Running the calculated properties from analysis 1 gives RI=1.740,  SG.= 3.747,  sus= 10.49, and cell constant= 11.5073.”

 

 

 

 

 

 

 

 

 

 
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Dr. Don Hoover

Dr. Donald Hoover is a retired research geophysicist with the U.S. Geological Survey who now pursues independent gemological research in Springfield, Missouri.