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Table 2 Representative electron probe results for cristobalite and quartz phases

From: The structure of volcanic cristobalite in relation to its toxicity; relevance for the variable crystalline silica hazard

  Prismatic cristobalite Platy cristobalite Devitrification quartz Quartz phenocryst
MVO617 MontR1 MVO1406 MVO819 MVO819 MVO1236 MontR1 MontR1 MVO945 MVO287
Na2O 1.14 0.30 0.41 0.98 0.70 0.96 0.14 n.d. n.d. n.d.
Al2O3 1.94 1.42 0.96 2.74 1.50 1.71 0.62 0.09 0.25 n.d.
SiO2 96.16 97.42 98.32 94.73 96.10 96.65 99.27 99.49 100.08 100.10
MgO n.d. 0.02 n.d. 0.04 0.12 n.d. 0.02 n.d. n.d. n.d.
K2O 0.01 0.03 0.23 0.60 0.26 n.d. 0.03 0.13 n.d. 0.01
CaO 0.08 0.29 0.02 0.12 0.08 0.06 0.47 0.22 0.05 n.d.
TiO2 0.23 0.09 0.17 0.17 0.17 0.15 0.11 0.08 0.08 0.03
MnO n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.
FeO 0.20 0.20 0.09 0.34 0.37 0.19 0.16 0.29 0.15 n.d.
Total 99.79 99.77 100.19 99.75 99.27 99.75 100.81 100.12 100.64 100.21
  1. Data are in oxide wt. %. n.d. = not detected.