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Table 2 Representative chemical compositions of pyrope from Garnet Ridge

From: Hydrous Na-garnet from Garnet Ridge; products of mantle metasomatism underneath the Colorado Plateau

 

(A) Cr-rich pyrope

(B) Cr-poor pyrope

B1

B2

B3

B4

Wt.%

Amp

Ilm-only

Dense lamellae

Cpx-Amp

SiO2

41.91

42.24

41.02

41.32

40.40

TiO2

0.09

0.05

0.14

0.10

0.06

Al2O3

22.30

23.36

21.66

23.01

22.72

Cr2O3

1.71

0.13

1.46

0.01

0.04

FeOa

8.80

9.26

13.82

14.49

19.7

MnO

0.36

0.38

0.54

0.41

0.45

MgO

19.31

18.75

15.81

15.85

13.33

CaO

5.43

5.99

5.43

4.93

3.41

Na2O

0.02

0.02

0.03

0.05

0.05

K2O

0.00

0.00

0.00

0.00

0.00

Total

99.92

100.18

99.91

100.17

100.15

Cations

Number of cations on the basis of 12 oxygen

Si

3.000

3.009

3.007

3.007

3.001

Ti

0.005

0.003

0.008

0.006

0.003

Al

1.881

1.961

1.871

1.974

1.989

Cr

0.097

0.008

0.085

0.001

0.002

Fe3+

0.019

0.023

0.034

0.016

0.004

Fe2+

0.498

0.517

0.797

0.857

1.218

Mn

0.022

0.023

0.034

0.025

0.029

Mg

2.060

1.991

1.728

1.719

1.476

Ca

0.416

0.457

0.426

0.384

0.271

Na

0.002

0.002

0.004

0.007

0.006

K

0.000

0.000

0.000

0.000

0.000

Total

7.999

7.994

7.992

7.996

8.001

  1. aTotal Fe as FeO