Melilite- and Leucite-Bearing Systems - Origin of Potassium-rich Silica-deficient Igneous Rocks - page 307

Fig. 10.2 Phase relation in
the join forsterite - diopside -
leucite at 1 atmosphere (after
Gupta 1972)

(Forsterite)

MgSiO 4

0

(1493 C)

Fo ss

g

1380

1360

Lc ss

Di ss

1340

v v v v v v v v

v

i

0

KAlSi 26
(Leucite)

CaMgSi 26
(Diopside)

(1296 C)

0

(1302 C)

Fig. 10.3 Phase relation in
the join forsterite - akermanite
- leucite at 1 atmosphere (after
Gupta 1972)

Mg Si 2 4
(Forsterite)

Fo s s
1440
1400
1360

0

(1493 C)

Mo ss

1 38 0
1320
1286 0

H

Lc ss

G

Ak ss

v v

v v v v v v

KAlSi 26
(Leucite)

Ca MgSi O
2

0

2 7

K (1297 C)

(Akermanite)

10.1.1.4 The Join Forsterite - Diopside - Akermanite

This join was studied by Ferguson and Merwin (1919) as a part of the system
CaO C (estimated from their

diagram) forsterite ss + monticellite ss +akermanite ss + liquid are in equilibrium. Another

MgO SiO 2 . They found that at Fo 17 Ak 77 Di 6 and 1,430 °

- -