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Cristallo is a glass which is totally clear (like rock crystal), without the slight yellow or greenish color originating from iron oxide impurities. This effect is achieved through small additions of manganese oxide.〔R. W. Douglas: ''A history of glassmaking'', G T Foulis & Co Ltd, Henley-on-Thames, 1972, ISBN 0-85429-117-2.〕 Often Cristallo has a low lime content which makes it prone to glass corrosion (otherwise known as glass disease). The invention of Cristallo glass is attributed to Angelo Barovier around 1450.〔Carl I. Gable, ''Murano Magic: Complete Guide to Venetian Glass, its History and Artists'' (Schiffer, 2004), p. 24. ISBN 0-7643-1946-9.〕 ==Materials== In addition to common glass making materials manganese, quartz pebbles, and alume catino are used in the making of cristallo glass. Rather than using common sand, crushed quartz pebbles were used instead. The quartz pebbles were typically from the Ticino and the Adige rivers. The quartz pebbles went through a rigorous screening process before being selected for use in cristallo production. The quartz pebbles had to be free of yellow and black veins and also had to be able to produce sparks when struck with steel. If the quartz pebbles passed the selection process then the pebbles were heated to the point where the stones began to glow and then paced into cold water. Then the pebbles were crushed and ground. The typical flux was used in the production of cristallo was called alume catino. Alume catino was derived from the ash of the salsola soda and salsola kali bushes that grew in the Levantine coastal region. The ash of the plants was then carefully sieved and then placed into water to be gently boiled with constant mixing. Then the ashen mixture was placed into shallow pans to be dried. Once dried the alume catino would repeat the boiling and drying process until all of the salt was extracted from the ashes. 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「Cristallo」の詳細全文を読む スポンサード リンク
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