Table 2

Mineral compositions of Al-tobermorite in relic lime clasts A–E from Baianus Sinus and Portus Neronis, in weight percent (wt%) of oxides, by EPMA (Fe2O3 represents “total iron”)

Baianus Sinus (Bay of Pozzuoli)Portus Neronis (Anzio)Tobermorite
Oxide3σ LLD*BAI.06.03 ABAI.06.03 BBAI.06.03 CBAI.06.03 DANZ.02.01 ESkyeIdeal
±2σ§±2σ±2σ±2σ±2σ±2σ±2σ±2σ±2σ±2σ±2σ
SiO20.0438.70.539.70.539.00.539.50.539.10.538.60.538.60.539.00.540.60.539.40.539.90.548.148.2
Al2O30.047.10.27.00.27.10.27.30.27.10.26.70.27.00.27.10.27.10.27.70.28.10.24.00.0
Fe2O30.13<0.130.0<0.130.0<0.130.0<0.130.0<0.130.0<0.130.0<0.130.00.20.2<0.130.0<0.130.00.20.00.00.0
MgO0.020.20.10.20.10.10.00.40.10.20.10.70.10.20.10.10.00.00.01.80.11.70.10.00.0
CaO0.0335.00.535.20.535.10.534.70.534.90.533.90.534.50.533.80.535.00.532.90.532.40.535.237.4
Na2O0.050.70.10.60.11.20.21.50.21.60.20.70.11.40.22.20.21.90.21.70.22.50.20.00.0
K2O0.031.00.11.00.11.00.11.20.11.20.10.90.11.00.10.90.10.80.10.70.10.90.10.00.0
Sum82.70.783.60.783.40.884.40.884.10.881.60.782.80.883.30.885.40.884.20.885.80.887.385.6
H2O||11.011.311.311.411.311.011.011.111.611.712.012.514.4
100
Number of atoms per formula unit based on 18[O, (OH)]
Si4.80.044.90.034.80.044.80.044.80.044.80.044.80.044.80.044.90.034.80.044.70.045.56.00
Al1.00.031.00.031.00.031.00.031.00.031.00.031.00.031.00.031.00.031.10.031.10.030.50.00
Fe3+0.00.000.00.000.00.000.00.000.00.000.00.000.00.000.00.020.00.000.00.000.00.000.00.00
Mg0.00.010.00.010.00.010.10.010.00.010.10.020.00.010.00.010.00.010.30.020.30.020.00.00
Ca4.60.064.60.064.60.064.50.064.60.064.60.064.60.064.50.064.50.064.30.064.10.064.35.00
Na0.20.030.10.030.30.040.30.040.40.040.20.030.30.040.50.050.40.040.40.040.60.050.00.00
K0.20.010.20.010.20.010.20.020.20.020.10.010.20.010.10.010.10.010.10.010.10.010.00.00
Sum10.80.0810.80.0810.90.0910.90.0911.00.0910.80.0910.90.0911.00.0910.90.0910.90.0911.00.0910.311.00
Ca/(Al+Si)0.800.790.790.770.790.780.790.760.770.730.700.680.78
Al/(Al+Si)0.180.170.180.180.180.170.180.180.170.190.190.080.00
  • * Lower limit of detection.

  • Analysis 8 in Livingstone (1988, p. 712), also quoted as analysis 2 in Anthony et al. (1995, p. 808).

  • Ideal tobermorite of stoichiometric composition without impurities.

  • § Calculated by propagating the analytical uncertainty following Giarimita and Day (1990).

  • || Calculated by stoichiometry.