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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.