Hostname: page-component-745bb68f8f-s22k5 Total loading time: 0 Render date: 2025-01-11T10:50:12.442Z Has data issue: false hasContentIssue false
  • English
  • Français

Itoigawaite, a new mineral, the Sr analogue of lawsonite, in jadeitite from the Itoigawa-Ohmi district, central Japan

Published online by Cambridge University Press:  05 July 2018

H. Miyajima ,
S. Matsubara ,
R. Miyawaki  and
K. Ito
H. Miyajima
Affiliation:
Fossa Magna Museum, Itoigawa, Niigata 941-0056, Japan
S. Matsubara
Affiliation:
Department of Geology, National Science Museum, Tokyo 169-0073, Japan
R. Miyawaki
Affiliation:
Department of Geology, National Science Museum, Tokyo 169-0073, Japan
K. Ito
Affiliation:
Membership of Fossa Magna Museum, Itoigawa, Niigata 941-0056, Japan
Get access Rights & Permissions [Opens in a new window]

Abstract

Itoigawaite, SrAl2Si2O7(OH)2·H2O, is a new member of the lawsonite group found in the Itoigawa-Ohmi district, central Japan. It is orthorhombic, Cmcm, a = 6.031(2), b = 8.945(2), c = 13.219(4) Å, Z = 4. The strongest lines in the X-ray powder diffraction pattern are 4.68 (s) (111), 4.26 (vs) (021), 3.31 (vs) (113), 2.75 (vs) (114, 202), 2.68 (vvs) (130), 2.63 (s) (131), 2.50 (s) (220, 203, 132), 2.45 (s) (221). Electron microprobe analysis gave SiO2 32.98, TiO2 0.87, Al2O3 27.67, Fe2O3 0.39, MgO 0.27, CaO 0.45, SrO 27.71, H2O (diff.) 9.66, total 100.00 wt.%, corresponding to (Sr0.97Ca0.03Mg0.02)Σ1.02 (Al1.97Ti0.04Fe0.02)Σ2.03Si1.99H3.89O10 on the basis of O = 10. It is transparent, blue in colour with vitreous lustre. The streak is white and the cleavage good in one direction. The hardness is 5–5.5. The calculated density is 3.3 g cm−3. It is colourless in thin section and optically biaxial positive with α = 1.664 (2), β = 1.674 (2), γ = 1.688 (2) and 2V(calc.) = 81°. It occurs in a thin veinlet cutting a lavender-coloured Ti-bearing jadeitite. The veinlet includes irregularly-shaped aggregates composed of minute tabular crystals of itoigawaite up to 50 µm across and minute jadeite crystals with interstitial natrolite aggregates. Itoigawaite is considered to be crystallized from fluid during later stage activity of high-P/T metamorphism. The name is for the locality.

Keywords

itoigawaitenew mineralstrontiumjadeitejadeititelawsoniteRenge metamorphic beltItoigawa-Ohmi district, Japan
Type
Research Article
Information
Mineralogical Magazine , Volume 63 , Issue 6 , December 1999 , pp. 909 - 916
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1999

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Armbruster, T., Oberhänsli, R., Bermanec, V. and Dixon, R. (1993) Hennomartinite and kornite, two new Mn3+ rich silicates from the Wessels Mine, Kalahari, South Africa. Schweiz. Mineral. Petrogr. Mitt., 73, 349–55.Google Scholar
Davis, G.A. and Pabst, A. (1960) Lawsonite and pumpellyite in glaucophane schist, North Berkeley Hills, California, with notes on the X-ray crystallography of lawsonite. Amer. J. Sci., 258, 689–704.CrossRefGoogle Scholar
Griffen, D.T., Ribbe, P.H. and Gibbs, G.V. (1977) The structure of slawsonite, a strontium analogue of paracelsian. Amer. Mineral., 62, 31–5.Google Scholar
Kawachi, Y., Coombs, D.S. and Miura, H. (1996) Noélbensonite, a new BaMn silicate of the lawsonite structure type, from Woods mine, New South Wales, Australia. Mineral. Mag., 60, 369–74.CrossRefGoogle Scholar
Kawano, Y. (1939) A new occurrence of jade (jadeite) in Japan and its chemical properties. J. Japan. Assoc. Mineral. Petrol. Econ. Geol., 22, 195–201. (in Japanese).Google Scholar
Kobayashi, S., Miyake, H. and Shoji, T. (1987) A jadeite rock from Oosa-cho, Okayama Prefecture, Southwestern Japan. Mineral. J., 13, 314–27.CrossRefGoogle Scholar
Miyajima, H., Matsubara, S., Miyawaki, R. and Hirokawa, K. (1998 a) Strontiochevkinite and tausonite in blue jade from the Itoigawa district, the Hida marginal belt, central Japan. Abstracts of 1998 Japan Earth and Planetary Science Joint Meeting, p. 247. (in Japanese).Google Scholar
Miyajima, H., Matsubara, S., Miyawaki, R. and Ito, K. (1998 b) Sr analogue of lawsonite in jade from the Itoigawa district. Annual Meeting Abstracts of the Mineral. Soc. Japan, p. 18. (in Japanese).Google Scholar
Miyajima, H., Matsubara, S., Miyawaki, R. and Ito, K. (1998 c) Lamprophyllite in jade from the Itoigawa district. Annual Meeting Abstracts of the Mineral. Soc. Japan, p. 83. (in Japanese).Google Scholar
Miyajima, H., Matsubara, S., Miyawaki, R., Hirokawa, K. and Ito, K. (1998 d) Strontium minerals in jade from Itoigawa-Ohmi district. Annual Meeting Abstracts of the Japan. Assoc. Mineral. Petrol. Econ. Geol., p. 175. (in Japanese).Google Scholar
Nakajima, T., Ishiwatari, A., Sano, S., Kunugiza, K., Okamura, M., Kano, T., Soma, T. and Hayasaka, Y. (1992), Geotraverse across the Southwest Japan Arc: an overview of tectonic setting of Southwest Japan. In 29th IGC Field Trip Guide Book, vol.5: Metamorphic belts and related plutonism in the Japanese Islands (Kato, H. and Noro, H., eds). Geol. Surv. Japan, A25, pp. 1–83.Google Scholar
Nishimura, Y. (1998) Geotectonic subdivision and arealextent of the Sangun belt, Inner Zone of Southwest Japan. J. metam. Geol., 16, 129–40.CrossRefGoogle Scholar
Ohmori, K. (1939) Optical properties of jade (jadeite) newly occurred in Japan. J. Japan. Assoc. Mineral. Petrol. Econ. Geol., 22, 201–12. (in Japanese).Google Scholar
Tagai, T., Hoshi, T., Suzuki, M., Kato, A. and Matsubara, S. (1995) A new modification of slawsonite, SrAl2Si2O8: Its structure and phase transition. Zeits. Kristallogr., 210, 741–5.Google Scholar