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napoleonite Napoleonite, is a variety of diorite (also called corsite because the stone is found in the island of Corsica). ==Description== Napoleonite is a variety of diorite which is characterized by orbicular structure. The grey matrix of the stone has the normal appearance of a diorite, but contains many rounded lumps 1 or 2 inches in diameter, which show concentric zones of light and dark colors. In these spheroids also a distinct and well-marked radial arrangement of the crystals is apparent. The center of the spheroid is usually white or pale grey and consists mainly of feldspar; the same mineral makes the pale zones while the dark ones are rich in hornblende and pyroxene. The feldspar is a basic variety of plagioclase (anorthite or bytownite). Though mostly rounded, the spheroids may be elliptical or subangular; sometimes they are in contact with one another but usually they are separated by small areas of massive diorite.
抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「napoleonite」の詳細全文を読む
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