Mineral:  Biotite K(Mg,Fe+2)3(Al,Fe+3)Si3O10(OH,F)2

Sample No.: biotite.1

XRD Analysis:  Pure biotite.

Chemistry:  Microprobe analysis was difficult because of sample 
mounting problems, but the sample seemed to be homogeneous 
within and between grains.  An average of 5 analyses showed 
sufficient magnesium that this might almost be classified as a 
phlogopite:

SiO2	38.21
Al2O3	 15.72
FeO	9.58
MgO	18.72
CaO 	0.13
K2O 	9.24
Na2O	0.20
TiO2	2.16
Cr2O3	0.05
	_____
Total	*94.01
*OH and F not measured
