Table 7. Microprobe analytical compositions of olivine.

[Oxide values are in weight percent]

Rock type
Sample

Dacite

 

Andesite

 

Basalt

Pt26
K1
core

rim

Pt41
K2
core

rim

Pt46
K3
core

rim

Pt42
K5
core

rim

K2
core

rim

Pt53
K5
core

rim

SiO2

41.06

41.27

40.90

40.46

40.07

40.50

 

42.05

41.63

41.08

41.10

 

40.50

41.27

FeO

11.28

12.94

11.00

13.08

13.31

13.40

 

10.46

11.02

11.47

13.09

 

11.02

12.66

MnO

.16

.26

.21

.24

.24

.25

 

.19

.21

.22

.24

 

.21

.22

MgO

46.38

45.85

47.28

46.25

45.98

46.39

 

45.88

46.33

47.74

46.87

 

48.34

47.04

CaO

.19

.25

.16

.18

.18

.20

 

.16

.15

.17

.21

 

.19

.22

NiO

.23

.16

.25

.18

.21

.14

 

.28

.25

.22

.12

 

.22

.16

     Total

99.30

100.73

99.80

100.39

99.99

100.88

 

99.02

99.59

100.90

101.63

 

100.48

101.57

Number of cations on the basis of 4 oxygens

Si

1.018

1.017

1.010

1.003

.999

1.001

 

1.040

1.027

1.005

1.005

 

.995

1.008

Fe

.234

.267

.227

.271

.278

.277

 

.216

.227

.235

.268

 

.226

.259

Mn

.003

.005

.004

.005

.005

.005

 

.004

.004

.005

.005

 

.004

.005

Mg

1.715

1.684

1.740

1.709

1.710

1.709

 

1.691

1.704

1.741

1.709

 

1.770

1.712

Ca

.005

.007

.004

.005

.005

.005

 

.004

.004

.004

.006

 

.005

.006

Ni

.005

.003

.005

.004

.004

.003

 

.006

.005

.004

.002

 

.004

.003

     Total

2.980

2.983

2.990

2.997

3.001

3.000

 

2.961

2.971

2.994

2.995

 

3.004

2.993

Fo

88.0

86.3

88.5

86.3

86.0

86.1

 

88.7

88.2

88.1

86.4

 

88.7

86.9

This page is <https://pubs.usgs.gov/pinatubo/bernard/table7.html>
Contact: Chris Newhall
Last updated 03.29.99