Surface Microtopography of Pyrophyllite: Photograph Collection

The surface microtopographies of pyrophyllite crystals from various localities has been investigated by using transmission electron microscopy (TEM) with the Au-decoration technique. The pyrophyllite specimens investigated were collected from the southern Urals (Russia), California (USA), the north part of Vietnam, the southwestern part of Korean Peninsula and southwest Japan. Gold-decoration successfully revealed growth steps (～1 nm in height) on the crystal surfaces. Pyrophyllite specimens from schistose and massive ores exhibit characteristically parallel growth patterns with narrow step separation, whereas polygonal spiral growth patterns with wider step separation are observed on crystal surfaces of pyrophyllite in veins. The morphology of pyrophyllite crystals seems to reflect the growth processes under different conditions (temperature and/or supersaturation), e.g., parallel steps on the irregular particles, on the other hand, polygonal spiral steps on polygonal plates

Surface Microtopographs of Clay Minerals

By means of transmission electron microscopy (TEM) and the gold-decoration technique, the surface microtopography of day minerals collected from various mode of occurrence were investigated. The clay minerals investigated exclusively exhibit many kinds of patterns on their crystal surfaces, such as growth, cleavage, aggregation patterns and so on

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

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