| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1986: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Mineralogical properties of the so-called sericite minerals associated with some Roseki deposits in the Chugoku provinces have been investigated by X-ray diffraction, chemical and thermal analytical methods.
The sericite minerals constituting a typical Roseki deposit of the Yagi mine in the Mitsuishi district, Okayama Prefecture, yield noticeable substitution of ammonium for interlayer potassium and variable interstratification with montmorillonite showing a remarkable tendency to increase from silicified zone to intensely sericitized (Roseki) zone through spotted "Toseki" zone. On the contrary, the minerals occurring in a "high-temperature" type Roseki deposit of the Uku mine, Yamaguchi Prefecture, are well-crystallized <2M_1> sericite having neither interlayer substitution nor mixedlayering with montmorillonite. The specimens from a "telescope" type Roseki deposit of the Horo mine, Hiroshima Prefecture, are of intermediate nature between the typical and "high-temperature " type deposits.
Additionally thermal properties of these seicite minerals are to be noticed in relation to interlayer substitution of ammonium for potassium. Usual potassium mica yield simple dehydroxylation around 500-600゜C. Ammonium-bearing mica, however, forms H-mica structure at once by detachment of ammonia from the interlayer ammonium at 400-500゜C and then slow dehydroxylation takes place at relatively high temperature range of 700-800゜C followed by subsequent transformation to mullite and silica mineral at about 1000゜C. This thermal behavior is accompanied with distinctive volume constraction, which is considered to be an important character in utilizing as ceramic materials.
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