The rate of decolorization of a Norwegian amazonite was studied at various temperatures: near 500° C. it was almost instantaneous, becoming successively slower with lower temperatures, until at 300° C. no change was visible in 10 hours. It is concluded that the colour is stable indefinitely below about 270° C. and that this is the maximum temperature at which the colour could have appeared.

Sixteen samples of Middle and Upper Chalk from the Chilterns yielded what appear to be fragments of fish scales, spines, and bones, which consist of collophane. X-ray examination by the powder method shows that the material has an apatite-type structure with cell dimensions close to those previously reported for francolite. Examination of single grains shows that the optical anisotropy is due to preferred orientation of the c-axes of the crystallites and this direction corresponds to the faster vibration direction. Such grains are found to be pseudouniaxial negative. Preferred orientation could not be detected in isotropic grains.

A singly terminated transparent, deep-garnet-red crystal originally weighing 1·7g. from a gem gravel from Mogok, Burma, proves to be a new mineral having Al2O3 76·2, SiO2 5·6, B2O3 2·2, CaO 15·7, H2O 0·7, Fe2O3 and MnO traces, total 100·4. Sp. gr. 4·01; ω 1·8159, ɛ 1·7875; H 8. The hexagonal unit cell has a 8·725, c 8·46 Å., space group P63, P63/m or P63 22, and contains approximately 38 O. The name painite is proposed in honour of A. C. D. Pain who recognized the unusual nature of the crystal.