著者

Nobuhide MURAKAMI Toshio KATO Yasunori MIÚRA Fumitoshi HIROWATARI

出版者

Japan Association of Mineralogical Sciences

雑誌

Mineralogical Journal (ISSN:05442540)

巻号頁・発行日

vol.8, no.2, pp.110-121, 1976 (Released:2007-03-31)

参考文献数

18

被引用文献数

5 18

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Sugilite occurs as an essential mineral amounting to 3–8 percent by volume in aegirine syenite from Iwagi Islet, Ehime Prefecture. It is associated with albite, aegirine, pectolite and a Ca-K-Ti silicate (a still to be identified mineral). Sugilite is light brownish yellow, luster vitreous, streak white. Symmetry hexagonal. Cleavage 0001 weak. Hardness 6–61/2. Specific gravity 2.802 (calc.), 2.74 (meas.).Under the microscope, it is uniaxial negative with ε=1.607, ω=1.610, ω−ε=0.003, and colorless.Estimated chemical composition is SiO2 71.38, TiO2 0.51, A12O3 2.97, Fe2O3 12.76, FeO 0.19, Li2O 3.14, Na2O 4.37, K2O 3.76, H2O(+) 0.81, H2O(−) 0.12, total 100.01%, corresponding ideally to (K, Na)((H2O), Na)2(Fe3+, Na, Ti, Fe2+)2(Li, Al, Fe3+)3(Si12O30) with Z=2.The unit cell dimensions are a0=10.007(2), c0=14.000(2)Å. Space group D26h−P6⁄mcc. X-ray powder data resemble those for sodgianite, milarite, osumilite, merrihueite, roedderite and brannockite.It is clear from the above-cited data that sugilite has milarite-type structure and resembles sodgianite and brannockite in containing lithium in tetrahedral site, but it is distinguished by a high content of ferric iron in 6-coordination.The name is given in honour of the late Professor Ken-ichi Sugi (1901-1948), who first found the occurrence of this mineral with Mr. M. Kutsuna.

著者

Toshio KATO Yasunori MIÚRA Nobuhide MURAKAMI

出版者

Japan Association of Mineralogical Sciences

雑誌

Mineralogical Journal (ISSN:05442540)

巻号頁・発行日

vol.8, no.3, pp.184-192, 1976 (Released:2007-03-31)

参考文献数

13

被引用文献数

2 15

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Crystal structure of sugilite has been refined by the least squares method using 435 reflections measured on an automated single crystal diffractometer using MoKα radiation. The final unweighted R-factor is 0.047 for 429 reflections. The cell dimensions are: a=10.007(2), c=14.000(2)Å; space group P6⁄mcc. Sugilite is isostructural with milarite group minerals, and can be described as (K0.81Na0.19)[12] (H2O0.91Na0.64)2[9] (Fe3+1.32Na0.59Ti4+0.06Fe2+0.03)2[6] (Li2.12Al0.59Fe3+0.29)3[4]Si[4]12O30 with Z=2 by structure formula of milarite group defined by Forbes, Baur and Khan (1972). The SiO4 tetrahedra from hexagonal double rings with the composition Si12O30. These double rings are linked by Li, Al and Fe3+ atoms in tetrahedral four-coordination to form a tetrahedral frame structure. Na and H2O are located in nine-coordinated sites.