Fission track geochronology of 7 samples of apatite found at Borra Mine, Vishakhapatnam district, has been described. The mineral is widely disseminated as an accessory constituent in large variety of rocks and fission tracks in them can be readily etched. The tracks are etched in conc. HNO₃ and annealed in one hour at 400°C. Extrapolation of the experimentally determined temperatures for annealing suggests that a temperature of 170°C for one million year will erase all the tracks in the mineral. An absolute age of (456±4.7 m.y.) has been determined for the above mentioned district. The results have been compared with other minerals.

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The single crystals of rutile were grown from the flux of the system Li₂WO₄–WO₃. Their growth habits varied through three types, {110}>{101}, {110}>{111} and {111}>{110}≈{253}, with increasing WO₃ in the flux melt. TiO₂ solubility was measured to determine the reactivity between TiO₂ and WO₄ or WO₆ species in the flux melt. The heat of solution of TiO₂ into the Li₂WO₄ melt was determined to be 49 kcal/mol, and decreased markedly by adding WO₃ owing to the large reactivity of TiO₂ with WO₃ (or WO₆).
It is inferred that the habit modification of rutile was attributed to the steric interaction of WO₆ species which were epitaxially adsorbed on the growing surfaces.

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An apparatus for in-situ observation and precise measurement of growth rate of crystals from aqueous solutions which can be used in a non-thermostated room is constructed. The apparatus consists of 1) a thermostated vessel to prepare saturated solution with temperature control within ±0.01°C, 2) a growth cell which is used on the microscope stage, and 3) temperature control units. The temperature control units are newly designed by combining the on-off and continuous regulators by which temperature is controlled with an accuracy of ±0.01°C. Even in the growth cell operated in an ordinary room where temperature fluctuates largely, the temperature in the cell could be maintained within ±0.01°C fluctuation for about 30 minutes. Examples to demonstrate the capability of the apparatus are shown for growth rate measurements of NaClO₃ and KBr.

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Labradorescence in the color zoning, in which remarkable change of lamellar thickness and An content are observed, is discussed. A wide-area macro-analysis in the region of color zoning is performed by using “X-ray contour mapping” with computer controlled electron probe microanalyzer, which has hitherto been infeasible with conventional automated electron probe microanalyzer.
The result of mapping analysis in a wide area agrees with the Bøggild rule between An content and interference color reported by Miúra et al. (1975). In the region of color zoning, it is found that thickness of alternate lamellae and composition change mutually and remarkably. For the specimen showing color zoning in smaller region, it is extremely difficult to find a one-to-one correlation between An content and iridescence color which agrees with the Bøggild rule. In the region of smaller color zoning it is possible to find that blue region contains only 2–3% less An content than the red one. In color zoning through a few millimeters area, however, the compositional difference between blue and red regions is about 7 mole % An. An content obtained by electron probe microanalysis in the smaller region of red-iridescence shows lower value than that in the wider red region showing uniform iridescence color.

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Hydrothermal experiments were conducted at 1 kilobar total pressure to synthesize spurrite and tilleyite by using oxalic acid as the source of carbon dioxide. The experimental results obtained at 1 kilobar indicate that spurrite and tilleyite are stable at temperatures as low as 430°C and 450°C respectively.

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