Economic and Environmental Geology

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Table. 1.

Table. 1.

Representative electron probe micro analyzer (EPMA) results and the structural formulae of the phengites from the Jeongseon and Okgye area

NP GH IG BD
Min. Max. Min. Max. Min. Max. Min. Max.
SiO2 51.14 51.24 50.36 50.36 46.02 50.12 49.16 50.88
TiO2 0.08 0.03 0.30 0.30 0.83 0.36 0.08 0.12
Al2O3 24.26 22.20 25.89 25.89 30.13 25.34 28.81 25.77
FeO* 0.08 0.09 0.32 0.32 0.04 0.04 0.07 0.18
MnO 0.00 0.00 0.00 0.00 0.00 0.04 0.00 0.00
MgO 4.59 6.00 4.06 4.06 2.75 4.21 2.69 3.90
CaO 0.06 0.08 0.31 0.31 0.10 0.15 0.13 0.14
Na2O 0.16 0.07 0.10 0.10 0.10 0.14 0.03 0.05
K2O 10.78 10.89 10.69 10.69 10.91 10.82 11.07 10.83
sum 91.14 90.59 92.04 92.04 90.86 91.23 92.03 91.88
Si 7.0633 7.1396 6.9021 6.9021 6.4145 6.9295 6.7312 6.9702
Al(T) 0.9367 0.8604 1.0979 1.0979 1.5855 1.0705 1.2688 1.0298
Sum(T) 8.0000 8.0000 8.0000 8.0000 8.0000 8.0000 8.0000 8.0000
Al(O) 3.0123 2.7857 3.0837 3.0837 3.3637 3.0591 3.3810 3.1319
Ti 0.0080 0.0030 0.0311 0.0311 0.0871 0.0369 0.0083 0.0125
Fe(2+) 0.0088 0.0101 0.0369 0.0369 0.0044 0.0047 0.0078 0.0207
Mn 0.0000 0.0004 0.0003 0.0003 0.0000 0.0044 0.0000 0.0001
Mg 0.9445 1.2466 0.8303 0.8303 0.5708 0.8673 0.5487 0.7969
Sum(O) 3.9735 4.0458 3.9824 3.9824 4.0261 3.9725 3.9459 3.9621
Ca 0.0090 0.0115 0.0458 0.0458 0.0142 0.0224 0.0194 0.0211
Na 0.0439 0.0192 0.0271 0.0271 0.0273 0.0386 0.0066 0.0141
K 1.8993 1.9349 1.8685 1.8685 1.9396 1.9091 1.9341 1.8923
Sum 1.9523 1.9656 1.9414 1.9414 1.9811 1.9700 1.9601 1.9275

The structural formulae were calculated on basis of 22 oxygens.

*Total Fe is calculated as ferrous.

Econ. Environ. Geol. 2021;54:365-72 https://doi.org/10.9719/EEG.2021.54.3.365
© 2021 Econ. Environ. Geol.