COMMISSION GEOLOGIOUE - Arkisto.gsf.fi
COMMISSION GEOLOGIOUE - Arkisto.gsf.fi
COMMISSION GEOLOGIOUE - Arkisto.gsf.fi
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34 Bulletin de la Co=ission geologique de Finlande N: 0 212.<br />
Table 6. Chemical composition and the unit cell of eckermannite from Goldongri,<br />
India. Chemical analysis by Paavo Väänänen, M.Sc.,ofthe Geological Survey ofFinland.<br />
wt % I cation<br />
%<br />
Unit cell content<br />
SiO z 55.27 46.34 Si 15.51<br />
15.89 The umt eell:<br />
Al 2 ü 5<br />
1.16 1.14 Al 0.38<br />
Fe Z ü 5<br />
8.21 5.18 Fe 3 + 1. 73 a = 9.80 A<br />
Feü b = 17.91 ,)<br />
Mn 2 ü 5<br />
1.16 0.74 Mn 3 + 0.25<br />
e<br />
9.46<br />
= 5.29 »<br />
Mnü 0.00 ß = 104°6'<br />
MgO 17.75 Mg 7.42 Vo = 900.26<br />
Ti0 2<br />
0.29 22.18 Ti 0.06 Z =4<br />
CaO 4.95 0.18 Ca 1.49 Spaee group C 21m<br />
Na 2 0 7.95 4.44 Na 4.32 6.28 D = 3.099<br />
K 2 0 1. 32 12.92 K 0.47 Mg: (Mg+Fe+Mn) 0.79<br />
H 2 O+ 0.88 1. 40 OH 1.69<br />
H 2 O- 0.00 4.92<br />
45.66<br />
CO 2 n. d. °<br />
PbO n. d.<br />
CuO n. d.<br />
PzOs 0.80 0.56 P 0.19<br />
99.73 100.00<br />
Table 7. Optical properties of (mangan)eckermannite from India and of eckerman·<br />
nite from Norra Kärr, Sweden.<br />
a . .............. .<br />
ß··· · .. .. . .. . .. . .<br />
y . ... .... .... ... .<br />
2Va ........... .<br />
e: a . .. . ....... . .<br />
(Mangall)eckermallnite.<br />
Goldongri. India<br />
1.624 rose<br />
1. 631 light lila<br />
1.637 light blue<br />
72°<br />
49°<br />
Eckermannite, Norra Kärr.<br />
Sweden (Adamson. 1944)<br />
1.636 bluish green<br />
1. 6 44 light bluish green<br />
1. 649 pale yellowish green, almost eolourless<br />
75°<br />
25°_53°<br />
The calcium content of the mineral is quite high (4.95 wt % CaO). In<br />
this respect, it could be grouped with richterites and winchites. The optical<br />
properties of the mineral and the orietation of the optic axial plane (Fig. 1<br />
and Table 7) are so elosely related to eckermannite that the mineral here<br />
is classi<strong>fi</strong>ed with the eckermannite series. It is possible that many of the<br />
minerals called winchites have the same kind of relation to juddites as the<br />
eckermannite has to arfvedsonite.<br />
The X-ray powder data of the mineral are given in Table 3. The powder<br />
lines show a elose relationship to juddite.
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