Table 6

Representative electron-beam microprobe analyses of biotite.

Sample	356	356	407	458	JDD-94-05	JDD-94-07
	166.5	190	257.8	151.8
Analyses	15	1	6	7	15	11
	magmatic	magmatic	hydrothermal	magmatic	hydrothermal	hydrothermal
SiO2	41.65	41.11	40.53	36.63	40.68	40.57
TiO2	3.00	1.52	1.81	3.58	1.79	2.08
Al2O3	13.53	12.48	10.77	13.78	13.67	12.22
FeO	12.53	13.53	12.96	14.75	9.23	12.18
MnO	0.26	0.11	0.08	0.30	0.05	0.05
MgO	14.10	17.33	18.73	15.17	19.76	17.10
CaO	0.17	0.01	0.02	0.01	0.04	0.07
Na2O	0.98	0.14	0.14	0.23	0.28	0.15
K2O	9.46	9.83	9.08	9.47	9.87	8.68
F	1.94	2.03	2.57	0.87	3.27	2.37
Cl	0.18	0.11	0.13	0.21	0.10	0.13
CuO	0.00	n.a.	0.04	0.00	0.00	0.03
RbO	0.00	n.a.	0.08	0.00	0.00	0.06
V2O5	0.00	n.a.	0.04	0.00	0.00	0.01
H2O*	2.96	3.04	2.75	3.42	2.51	2.80
O=F	-0.82	-0.85	-1.08	-0.37	-1.38	-1.00
O=Cl	-0.04	-0.02	-0.03	-0.05	-0.02	-0.03
Total	99.90	100.37	98.45	98.00	99.84	97.38
Si4+	6.379	6.11	6.073	5.650	5.972	6.157
Ti4+	0.344	0.17	0.204	0.416	0.198	0.237
Al3+	2.443	2.19	1.903	2.506	2.365	2.185
Fe2+	1.599	1.68	1.626	1.905	1.134	1.547
Mn2+	0.033	0.01	0.010	0.039	0.006	0.007
Mg2+	3.202	3.84	4.184	3.484	4.326	3.867
Ca2+	0.028	0.00	0.003	0.001	0.006	0.012
Na+	0.290	0.04	0.039	0.149	0.079	0.043
K+	1.848	1.86	1.737	1.862	1.849	1.681
F-	0.933	0.95	1.219	0.424	1.519	1.135
Cl-	0.048	0.03	0.032	0.056	0.026	0.033
H+	3.019	3.02	2.749	3.520	2.455	2.832
O2-	24.061	23.34	22.869	23.806	22.777	23.195
Anion Sum	25.04	24.33	24.12	24.29	24.32	24.36

Formula calculated using program of Ercit (Unpublished) and on a basis of 24 anions