Summary: Members of the KAlSi₃O₈- BaAl₂Si₂O₈ feldspar series have been synthesized by hydrothermal methods. Although the products are too finely crystalline for complete detailed study, some X-ray and optical measurements have been made, together with some electron-diffraction observations.

The results presented confirm the existence of high structural states over the greater part of the series, and suggest that a simple solid-solution series is formed between the end-members at high temperatures.