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<front>
<journal-meta>
<journal-id journal-id-type="archive">gsminmag</journal-id>
<journal-title>Mineralogical Magazine</journal-title>
<abbrev-journal-title abbrev-type="full">Mineralogical Magazine</abbrev-journal-title>
<issn pub-type="ppub">0026-461X</issn>
<publisher>
<publisher-name>Mineralogical Society</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.1180/minmag.1980.043.331.05</article-id>
<title-group>
<article-title>Clinopyroxene with Si &#x003C; Al<sub>IV</sub> in the Join CaFeAlSiO<sub>6</sub>-CaTiAl<sub>2</sub>O<sub>6</sub></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>Onuma</surname>
<given-names>Kosuke</given-names>
</name></contrib>
<contrib contrib-type="author">
<name>
<surname>Akasaka</surname>
<given-names>Masahide</given-names>
</name></contrib>
<aff>Department of Geology and Mineralogy, Hokkaido University, Sapporo, 060, Japan</aff></contrib-group>
<pub-date pub-type="ppub">
<month>9</month>
<year>1980</year>
</pub-date>
<volume>43</volume>
<issue>331</issue>
<fpage>851</fpage>
<lpage>856</lpage>
<history>
<date date-type="received">
<day>28</day>
<month>1</month>
<year>1980</year>
</date>
<date date-type="rev-recd">
<day>7</day>
<month>3</month>
<year>1980</year>
</date></history>
<copyright-statement>Copyright &#x00A9; 1980, The Mineralogical Society</copyright-statement>
<copyright-year>1980</copyright-year>
<abstract>
<title>Summary</title>
<p>Unusual clinopyroxenes were synthesized in the study of the join CaFeAlSiO<sub>6</sub>-CaTiAl<sub>2</sub>O<sub>6</sub> in air at I atm. Clinopyroxene solid solution, hibonite solid solution, <italic>X</italic>-phase, perovskite, and corundum are present, and at subsolidus temperatures the clinopyroxene singlephase field extends up to about 19 wt% CaTiAl<sub>2</sub>O<sub>6</sub>. The CaTiAl<sub>2</sub>O<sub>6</sub> component in the clinopyroxene however increases beyond the clinopyroxene single-phase field and attains 23 wt%. These clinopyroxene solid solutions are extremely poor in SiO<sub>2</sub> and extremely rich in Al<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub>, and TiO<sub>2</sub>, and more than half of tetrahedral sites are occupied by Al<sub>IV</sub>, contravening the aluminium avoidance principle.</p></abstract>
</article-meta>
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</article>
