Study on the physical properties and genesis of borate minerals in skarns.

本研究旨在探讨冈山县福卡地区高温交代产物夕卡岩中的硼酸盐矿物的物理性质和成因。硼酸盐矿物赋存状态：矽卡岩矿物主要为高温交代产物，如硅铝石、闪锌矿等。在后交代阶段，夕卡岩被许多脉切割，脉由水化硅酸钙、含氟矿物和含硼矿物组成。沿结晶石灰岩和夕卡岩之间的边界发育的由硼酸盐矿物组成的矿脉。静脉的厚度约为10厘米，但有一部分扩张到3米。在扩张区的中心，出现了角斑岩。在扩张区的周缘，发育有厚度为20~50 cm的绿山石、泡沫石、水镁石、水镁石、寄生水镁石等含水硼酸盐。硼酸盐矿物的物理性质：通过本研究，揭示了许多硼酸盐矿物的光学性质、硬度、密度、X射线衍射性质、化学成分、热性质和红外吸收光谱等矿物学性质。硼酸盐矿物的成因：根据产出方式、硫化物矿物数据和Schafer(1968)报道的数据，这些矿物的形成可认为是：(1)含硼流体与石灰岩反应形成钠镁铁矿；(2)钠镁铁矿和寄生水镁石是由钠镁铁矿热液蚀变形成的；(3)晚期热液作用使锡矿和寄生水镁石转化为英钠闪锌矿、钙钛矿等。

The present study aims at claryfing the physical properties and genesis of borate minerals in skarns, which are formed as high-temperature metasomatic products at Fuka, Okayama Prefecture.1. Occurrence of borate minerals : Skarn minerals such as gehlenite and spurrite were primarily formed as high-temperature metasomatic products. During the post-metassomatic stage, the skarns were cut by numerous veins which consist of hydrated calcium silicates, fluoline-bearing minerals, and boron-bearing minerals. A vein consisting of borate minerals developed along the boundary between crystalline limestone and the skarns. The vein was approximately 10 cm in thickness, although in one part expanded to 3m. At the center of the expanded area, takedaite occurred. At the circumference of the expanded area, hydrous borates such as olshankyite, frolovite, sibirskite, borcarite and parasibirskite occurred 20 cm to 50 cm in thickness.2. physical properties of borate minerals : The mineralogical propertes such as optical properties, hardness, density, X-ray diffraction properties, chemical composition, thermal properties and Infrared absorption spectrum of many borate mineals, were revealed through this study.3. Genesis of borate minerals : From the mode of occurrence, the data on the sulphide minerals and the data reported by Schafer (1968), the formation of these minerals may be considered as follows : (1) takedaite was formed by reaction of boron-bearing fluids with limestone ; (2) sibirskite and parasibirskite were formed by hydrothermal alteration of takedaite ; (3) the late-hydrothemal solution converted sibirskite and parasibirskite to olshanskyite, frolovite, etc.