Spherulitic Textures Found in Pyrophyllite Ore Deposits, Shobara District, Southwest Japan: Photograph Collection

Abstract

Spherulitic textures are commonly found in pyrophyllite ore deposits in Shobara district, Hiroshima Prefecture, Japan. Color photographs of the mode of occurrence, hand specimens and characteristic micro-textures are presented. The spherulitic textures occur mainly in the upper most horizon of the ore deposits, i.e., in pyrophyllite zone and weakly altered host rhyolitic rocks. The size of the spherulites is from few millimeters to several centimeters in diameter and the spherulites with several millimeters diameter is the most predominant. Color of the spherulites is also variable such as grey, dark blue, dark purple and greenish color. Under the microscope, the textures can be divided into two types, one is "radiation" and the other is "aggregation" types, respectively. The aggregation type is further subdivided into a) with fine grain rim and b) with coarse grain rim. The constituent minerals of the spherulite are feldspar, quartz, pyrophyllite, sericite, diaspore, hematite and goethite