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The Binary System Anorthite (CaAl 2 Si 2 O 8 )—Åkermanite (Ca 2 MgSi 2 O 7 )
Author(s) -
WYS E. CHRISTIAAN,
FOSTER WILFRID R.
Publication year - 1956
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1956.tb15607.x
Subject(s) - anorthite , liquidus , melilite , diopside , mineralogy , orthorhombic crystal system , thermodynamics , geology , chemistry , crystallography , phase (matter) , spinel , crystal structure , physics , paleontology , organic chemistry
A study of the equilibrium relations in the system anorthite‐åkermanite has been made as a part of an investigation of the ternary system diopside‐anorthite‐åkermanite. The technique employed was the well‐known quenching method. The liquidus relations indicate that anorthite and åkermanite form a simple binary system, with a eutectic located at a composition 46 anorthite, 54 åkermanite (by weight) and at a temperature of 1234°± 2°C. There is strong reason to believe that pure åkermanite, rather than an aluminous melilite, crystallizes with anorthite from intermediate compositions. No evidence to support the alleged decomposition of åkermanite at or below 1325°C. was obtained, since åkermanite gave no indication of instability in the liquidus range of temperatures. The study sheds no light on the relations between anorthite and its hexagonal and orthorhombic polymorphs.