Experimental studies have been carried out along the diopside-jadeite join and along ternar13y compositions diopside-jadeite with 10 mol % acmite added, using coprecipitated gels as starting materials. Pressures between 1 and 30 kbar $P(H_{2}O)$ at temperatures 450 to 1200 °C were used. The solid solution limit between Di and Jd is $13 \pm 1$ mol % for pressures 1, 2 an d 3 kbar $P(H_{2}O)$. The ternary compositions vary widely in their cell parameters as a consequence of experimental difficulties encountered in sealing the capsules to outside components (oxygen mainly), as well as a result of the fact that starting materials were mixes of diopsidic pyroxene and jadeitic/acmitic glasses, the production of homogeneous gels having proved to be impossible. The synthesis of stoichiometric chloromelanite $(Di_{33}Jd_{33}Ac_{33})$ did not succeed for the same reason, in spite of the use of solid-state buffers.
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Con il contributo del Ministero per i Beni e le Attività Culturali