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Table 1 Chemical analyses and weathering indices

From: Spheroidal weathering of basalt from Gebel Qatrani, Fayum Depression, Egypt

  1 2 3 4 5 6 7 Av
Core-stone
SiO2 49.66 49.28 49.76 49.75 49.96 48.75 49.08 49.46
TiO2 2.19 2.08 2.12 2.12 2.1 2.33 2.89 2.26
Al2O3 13.67 14.63 14.41 14.42 14.7 12.9 15.15 14.27
Fe2O3T 14.98 13.91 13.82 13.88 13.58 13.62 13.58 13.91
MnO 0.13 0.15 0.15 0.15 0.15 0.16 0.15 0.15
MgO 6.68 6.92 6.95 6.96 6.62 6.19 6.33 6.66
CaO 9.72 9.41 9.94 9.84 10.03 9.84 9.76 9.79
Na2O 2.39 2.13 2.19 2.17 2.21 2.34 2.58 2.29
K2O 0.78 0.73 0.81 0.8 0.79 0.79 0.78 0.78
P2O5 0.26 0.21 0.21 0.21 0.22 0.24 0.3 0.24
LOI 0.50 0.61 0.31 0.25 0.21 0.85 0.66 0.48
Total 100.97 100.07 100.66 100.54 100.56 99.92 100.24 100.42
Weathering indices*
WIP 71.5 69.3 71.3 70.1 70.6 72.9 72.4 71.16
CIA 38.4 41.2 39.3 39.8 39.8 36.9 40.4 39.40
CIW 38.7 41.3 39.9 40.2 40.2 37.2 40.8 39.76
MIA(O) 37.4 38.0 37.0 37.1 37.5 36.0 38.3 37.33
Shell around core-stone
SiO2 50.68 52.21 52.68 48.73 48.90 50.70 50.11 50.57
TiO2 2.00 2.00 2.10 2.20 2.00 2.20 2.80 2.19
Al2O3 14.70 16.32 16.57 16.44 16.70 15.90 17.15 16.25
Fe2O3T 15.00 12.08 12.18 14.88 14.50 14.62 15.58 14.12
MnO 0.14 0.15 0.15 0.14 0.13 0.13 0.13 0.14
MgO 5.80 4.20 4.29 5.96 4.62 4.19 4.38 4.78
CaO 8.10 8.00 7.16 7.80 8.03 7.81 7.50 7.77
Na2O 2.00 2.00 2.00 2.01 2.00 1.90 1.99 1.99
K2O 0.72 0.70 0.65 0.65 0.70 0.70 0.72 0.69
P2O5 0.24 0.41 0.30 0.22 0.20 0.23 0.25 0.26
LOI 0.80 1.20 1.50 1.20 1.90 1.50 0.38 1.21
Total 100.16 99.27 99.76 100.73 100.72 99.87 100.99 100.21
Weathering indicesa
WIP 62.7 58.0 50.9 61.0 59.2 55.8 55.3 57.56
CIA 44.7 48.1 50.4 48.2 47.8 47.6 50.1 48.13
CIW 44.9 47.8 50.4 48.5 48.3 47.9 50.9 48.39
MIA(O) 41.2 46.0 47.3 44.2 46.4 47.3 49.0 45.91
  1. aSee text