• Journal of the Mineralogical Society of Korea
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• v.14 no.2
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• pp.119-127
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• 2001

FTIR spectroscopic study was undertaken on dickite and pyrophyllite with Si and Al cations in the far-infrared(Far-IR) and mid-infrared (Mid-IR) regions, respectively. Attempts were made to present bonding information and make assignments on the absorption bands of dickite in the Far-IR region. Dickites contain a small proportions or kaolinite or nacrite layers. FTIR can be used as a potential tool for characterizing the presence of mixed-layer with different polytypes of the kaolin minerals. There is no clear relationship between Hinckley index and crystallinity of dickite. Although pyrophyllite shows a strong OH stretching band at 3673-3676 $cm^{-1}$ / corresponding to an inner hydroxyl group, the weak band at $3645-3648 cm^{-1}$ seems to be due to the symmetric vibration if the symmetry of the structure is not ideal, probably due to the presence of trace Fe or mixture phases of 1Tc and 2M polytypes.

• Journal of the Mineralogical Society of Korea
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• v.3 no.1
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• pp.44-57
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• 1990

Mineralogy of clay(Napseok) deposits in Yangsan area has been studied by the methods of field investigation and laboratory works including the polarizing microscopy, X-ray diffraction, infrared spectroscopy, thermal analysis, chemical analysis by electron micro-probe and atomic absorption spectrophotometer, and electron microscopy(SEM and TEM). The Napseok ores in both the Cheonbulsan and Yongcheon deposits consist mainly of sericite, pyrophyllite and quartz, with more or less tourmaline. The high temperature minerals such as corundum and dumortierite are found in the Cheonbulsan deposit, but not in the Yongcheon deposits. Dickite, nacrite, and halloysite are found in the Yongcheon deposit, but not in the Cheonbulsan deposit. The Napseok ores of the Yukwang deposit consist of sericite posits in the Yangsan area. Occurrence, chemistry and structural features of important minerals are described. Mineralogical data of sericite such as intensity raios and chemistry also support that the Napseok deposits of both the Chenobulsan and Yongcheon mines were formed at the higher temperature than those of the Yukwang mine. Presence of sericite-dickite-pyrophyllite ores in the Yongcheon deposit also suggests the lower temperautre than in the Cheonbulsan deposit.

• Journal of the Mineralogical Society of Korea
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• v.4 no.1
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• pp.1-10
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• 1991

Tosudite from the Sungsan mine, Korea is an alteration product of rhyolitic tuff in the cretaceous Hwangsan Formation. It is associated with illite, dickite, nacrite or quartz and also found in the cavities of black claystone. X-ray diffraction and chemical analyses show that the Sungsan tosudite is a lithium-bearing aluminous 1:1 regularly interstratified mineral of di, dioctahedral chlorite and smectite. Its structural formula is $(K_{0.73}Na_{0.02}Ca_{0.07})(Si1_{13.23}Al_{2.77})(Li_{0.52}Mg_{0.08}Mn_{0.01)Fe^{3+}_{0.07}Al_{12.33})O_{40}(OH)_{20}$ and it suggests that Sungsan tosudite consists of regularly interstratified Li-donbassite and beidellite. DTA and TG curves as well as IR absorption data also support such a result. Temperature of formation of tosudite is inferred to be between $110{\circ}$ and $270{\circ}C$.