| The nature of the subsolidus phase relations in the system Be0-Al20 3-Si02-H20
in the temperature range 300° -700oc w& investigated at a water vapour pressure
of 15,000 psi. Phases synthesised were beryl, chrysoberyl, phenacite, mullite,
bertrandite, pyrophyllite, kaolinite, bromellite and quartz. The curve for the reaction
Beryl + H20~ Bertrandite + Pyrophyllite, demarcating the lower thermal
stability limit of beryl, was traced down to 3,000 psi. The hydrous compound bertrandite
gave indications of a fairly wide range of solid solution, suggesting
variability of the Be : Si ratio in its composition. |
