J. Japan. Assoc. Min. Petr. Econ. Geol. 67, 418-424, 1972

LEVYNE AND ERIONITE FROM CHOJABARU, IKI ISLAND, NAGASAKI PREFECTURE, JAPAN

MITSUO SHIMAZU and TADATO MIZOTA

Department of Geology and Mineralogy, Faculty of Science, Niigata University, Niigata, Japan

INTRODUCTION Levyne, a rare mineral found only in the Tertiary basalt lavas (Walker, 1960), was discovered for the first time in Japan at Chojabaru, Iki Island. Levyne occurs in coexistence with erionite in the amygdales of the altered basalts. Erionite is also a rare mineral, known to occur only at three localities in Japan, namely Maze, Sado and Narushima (Shimazu and Kawakami, 1967, Harada et al., 1967, Kawahara et al., 1967, Shimazu and Yoshida, 1969, and Muchi, Yamamoto and Tejima, 1972). In the present paper, the mode of Fig. 1. Locality map of Chojabaru, Iki Island. occurrence, mineral paragenesis, chemical composition and X-ray data of levyne and includes thin scoria and tuff. The diatomite erionite are described. contains fish and plant fossils, from which MODE OF OCCURRENCE as well as from the rock facies it is conjec Chojabaru is situated at the eastern tured that the Chojabaru formation had part of the Iki Island, northern Kyushu been deposited in the environment of lagoon (Fig. 1). Levyne and erionite mainly occur to lake. Alkali olivine basalt lavas of in the amygdales of the altered basalts of Pliocene to Pleistocene cover the Chojabaru the volcanic conglomerates exposed along formation. the seashore at Chojabaru. The volcanic Volcanic conglomerates are composed conglomerates belong to the Chojabaru for of subangular cobbles of the altered augite mation of the middle Miocene (Ishida et al., olivine basalt classified as tholeiite and 1970). The Chojabaru formation is divided coarse sand of basaltic materials. Volcanic into three part and its total thickness is 60 sandstones are composed of coarse sand of meters as far as observed. As shown in Fig. basaltic materials. Amygdales, 2 to 6mm., 2, the lower part is basalt lava and the filled with zeolites are conspicuous in the middle part is volcanic conglomerate and altered basalt cobbles which show dark volcanic sandstone. The upper part is grayish green or grayish black in colour. diatomite, sandstone and mudstone and Chabazite and stilbite are main zeolite

(Manuscript received, August 20, 1972) Levyne and erionite from Chojabaru, Iki Island, Nagasaki Prefecture, Japan 419

Fig. 2. Columnar section and occurrence of zeolites in the Chojabaru formation.

Fig. 3. Levyne (Le), erionite and stilbite (St) in the Fig. 4. Microphotograph showing the intergrowth basaltic rocks. Lustrous parts are erionites. of levyne (Le) and erionite (Er). 420 M. Shimazu and T. Mizota

minerals and these are accompanied by nite is uniaxial positive with ƒÃ=1.467 and

levyne, erionite, pbillpsite, natrolite and fibers are elongated parallel to Z (Fig. 4).

thomsonite. Zeolite minerals such as chaba

zite and thomsonite also occur in a vein CHEMICAL COMPOSITION

form of several milimeters in width, or Since erionite and levyne are minutely

cover sand grains in the volcanic sand intergrown and have not distinct difference

stones. in density, it was unsuccessful to separate

So far, levyne and erionite have been the two minerals. Therefore, chemical found at two locations. Levyne is closely Table 1. Chemical compositions of levynes intergrown with erionite in amygdales and and erionites by X-ray microanalyser sometimes is associated with chabazite and

stilbite. Chabazite occurs abundantly, fill

ing amygdales. It occurs as transparent

rhombohedral crystals, or as radial aggre

gates of elongated crystals, the length of which reaches to 2mm..

Stilbite also occurs abundantly and

forms radial aggregates growing from the

wall of amygdale to the center. It is

transparent, and the crystals attain 4mm.

in length. Thomsonite occurs in amygdales

or veinlets as radial aggregates of translu

cent or milky white fibrous crystals. Natro

lite occurs rarely in associated with thom

sonite, and shows similar fibrous habit.

Phillipsite occurs as milky white crystals having no distinct crystal plane in most

cases, and rarely as interpenetrating twin.

The main paragenesis of zeolite minerals are as follows; levyne-erionite, levyne-erio nite-stilbite, chabazite-stilbite and thomso nite-stilbite (Fig. 2).

PHYSICAL PROPERTIES

Crystals of levyne are thin tablar parallel to (0001), about 0.05mm. in width, and always show interpenetrate twin (Fig.

3). They are transparent with vitreous luster. Erionite generally shows parallel intergrowth with levyne, wooly fibers of the former lying normal to the (0001) plane of the latter. Levyne is uniaxial negative with

=1.490 and very low birefrengence . ErioƒÖ Levyne and erionite from Chojabaru , Iki Island, Nagasaki Prefecture, Japan 421 compositions were obtained by electron da et al., 1967) was used as standard microprobe. Microprobe analyses were materials. Chemical compositions of levyne made with Shimazu ARL electron microprobe and erionite are shown in Table 1. Levyne X-ray analyser Model EMX-2 with a 52.5•K and erionite from Beech Creek, Oregon were take off angle. Erionite from Maze (Hara also analysed by the same method for

Table 2. X-ray powder data of levynes.

* Cu Ka (Ni filter) , 30 Kv, 15 mA. ** Cu Ka , Camera, diam. 57.3 mm., Strunz (1956) 422 M. Shimazu and T. Mizota

comparison. Erionite from Beech creek and a(lev.)//a(er.), c(lev.)//c(er.). also shows parallel intergrowth with levyne. J. V. Smith (1963) summarized the cry Refractive indices of levyne from Beech stal structures of rhombohedral and hexa Creek are co=1.506, E=1.497 and ƒÖ-ƒÃ= gonal zeolites based on the stackingse quenc 0.009. Levyne from Beech Creek is poor es of hexagonal ring sheets composed of in Na2O and K2O and is rich in CaO in silicatetrahedrons. The sequences of erio comparison with levyne from Iki. An ap nite and levyne were explained AABAAC..

preciable substitution of Ca by Na and/or and AABCCABBC...., respectively. It is K is seen in levynes. Difference of optical considered that the structural similarity of

data of both levynes may represent the erionite and levyne will enable the epita

difference in chemical composition. xial growth between the two minerals. The diffraction layers by erionite are shown in X-RAY STUDIES

Both powder method and single crystal

method using precession camera were appli

ed. X-ray diffraction powder data of levyne

are well coincident with the data of levyne

from the Antrim basalts shown by Strunz

(1956). The indexing of reflection on the basis of the space group is a new contribu

tion (Table 2). The unit cell constants are

a=13.428•}0.005A, c=22.662•}0.008A.

Powder data of erionite are well coin

cident with the data for the samples from

Durkee, Baker County (Staples and Gard,

1959) and from Maze (Shimazu and Kawa

kami, 1967).

X-ray precession photographs obtained

by a small tabular crystal separated from

the specimens of Iki Island showed the

diffraction spots which contradicted with

the space group (R3m) of levyne. These

patterns could be explained by levyne erionite epitaxy and twinning of levyne.-

The R3m patterns of levyne were

relatively strong but some of the weak

extra-spots showed hexagonal symmetry.

When the unit cell parameters of levyne Fig. 5. The first upper layer reciprocal lattice were taken to be hexagonal of a=13.28A parallel to [10.1]-c* plane. ƒÊ=30•K, ƒÄ= and c=22.5A, the unit cell size and orien 0.078, CoKa, Fe filter . Levyne, tation relations between levyne and erionite twinned levyne and erionite are shown "•›" and "•~" "•œ" of the specimen could be shown as; ,"L'" respectively in the upper figure. These are shown "L'" ,"L'" a(lev.)=a(er.), c(lev.)=3/2c(er.) and "E" in the lower photograph . Levyne and erionite from Chojabaru, Iki Island, Nagasaki Prefecture , Japan 423

Fig. 5. epitaxial erionite on or in that crystal. It The other weak diffraction patterns is not certain whether a small amount of were explained in terms of partial twin-ning erionite was remained, though it was sepa of levyne. The twinning was a kind of c rated, or small size erionite crystals were axis 60•K rotation which was same as that included in the levyne crystal. It is noted shown by Barrer and Kerr (1959). These that the diffraction spots of erionite are patterns are shown in Figs. 5 and 6. slightly diffused, which may be infered to The diffraction patterns parallel to the the small size effect in X-ray diffraction, c* axis are liable to be mistaken as the suggesting the existence of small inclusions super lattice pattern of main spots of of erionite. levyne structure, because of the close rela DISCUSSION tions between the unit cell and orientation by levyne and those of erionite (Fig. 5). Most of levynes are found in the

The X-ray extinction rules of these minerals amygdales of altered basalts. The most could be completely explained by the space widespread occurrence of levynes are in the group of levyne (R3m) and erionite (P63/ basalts of Antrim, Ireland (Walker, 1951, mmc). 1960). According Walker, in three types of

The crystal of levyne used in this assemblages; i.e. analcime-natrolite-levyne, experiment is tabular parallel to (001) and has chabazite-thomsonite-levyne, gmelinite-lev some complex crack textures on the surface, yne. Among the three types, levynes occur but we could not recognize optically the most frequently in the second assemblage, in which it is also associated with phillipsite and calcite. In the Chojabaru basaltic rocks, levyne shows similar association and is closely intergrown with erionite. Similar inter growth of the two minerals is seen in the specimen from Beech Creek, Oregon. Walker described that at least a half of the crystals in the Antrim basalt is alter ed to a fibrous mineral with satiny lustre, whose fibers lie normal to the (0001) of levyne. Similar fibrous minerals are found on levyne in the Deccan traps (Chatterjee, 1971, Fig. 1). It is conjectured that these fibrous minerals may be erionite or its variety, judg Fig. 6. hk. 2plane of levyne. This plane dose ing from the similarity in the occurrence not include erionite pattern. Though and properties with those of Chojabaru and this photograph looks like a pattern of hexagonal symmetry due to twin Beech Creek. It is also considered that ning of c-axis 60•K rotation, relatively intergrowth (or epitaxial growth) between strong spots show 3-fold axis perpen levyne and erionite crystals may be found dicular to this plane. ƒÄ=0.158, ƒÊ=20•K, CoKa/Fe filter. widely, judging from the structural charac 424 M. Shimazu and T. Mizota teristics of the two minerals. logy of the Chojabaru diatomite, Iki, Japan The formation of zeolite minerals such (in Japanese). Memoirs Nat. Sci. Mus. Tokyo, No. 3, 49-63. as levyne and others in the Chojabaru Kawahara, A., Takano, Y., Takabatake, M. and basaltic rocks is infered to meteoric water Uratani, Y. (1967), The composition and cry percolated at a time probably long after the stal structure of erionite from Maze, Niigata Prefecture, Japan. Sci. Papers Coll. General eruption of the basaltic rocks, as suggested Education, Univ. Tokyo. 17, 237-248. by Walker and others. Muchi, M., Yamamoto, H. and Tejima, M. (1972), ACKNOWLEDGMENTS The writers wish to Erionite from Naru-Shima, Nagasaki prefecture express their heartfelt thanks to the Iki (in Japanese). Geol. Soc. Jap., '72 meeting, preprint. research group, especially Messers S. Haya Shimazu, M. and Kawakami, T. (1967), Distribution shi, T. Urakawa and T. Sakata for their of zeolite and other minerals in the Maze basalts, Niigata Prefecture, Japan. Sci. Rept. kind help. Thanks are also due to Dr. M. Niigata Univ., Ser. E, No. 1, 17-32. Komatsu for electron microprobe analyses Shimazu, M. and Yoshida, S. (1969), Occurrence of and to Dr. K. Sakurai for providing with erionite from Iwayaguchi district, Osado area, Niigata Prefecture (in Japanese). Jour. Geol. specimens of levyne of Beech Creek and Soc. Japan, 75, 389-390. valuable advice and to Prof. I. Sunagawa Smith, J. V. (1963), Structural classification of for critical reading of the manuscript. zeolites. Mineral. Soc. Amer., Special Paper, 1, 281-290. REFERENCES Staples, L. W. and Gardon, J. A. (1959), The fibrous zeolite erionite; its occurrence, unit cell and Barrer, R.M. and Kerr, I. S. (1959),Intra crystal structure. Mineral. Mag., 32, 261-266. line channels in levynite and some related Strunz, H. (1956), Die Zeolithe, Gmelnit, Chabasit, zeolites. Trans. Faraday Soc., 55, 1915-1923. Levyn (Phakolith, Herschelit, Seebachit, Off Chatterjee, A.C. (1971), Levyne in the Deccan retit). Neues Jahrb. Mineral., Monatshefte 11, traps. Mineral.Mag. 38 528-529. 250-259. Deer, W.A., Howie, R.A. and Zussman,J. (1963), Walker, G. P. L. (1951), The amygdale minerals in Rock-formingminerals, 4, Longmans, London. the Tertiary lavas of Ireland I. The distribu Harada, K., Iwamoto, S. and Kihara, K. (1967), tion of chabazite habits and zeolites in the Erionite, phillipsite and gonnardite in the Garron plateau area, County Antrim , Mineral. amygdaleof altered basalt from Maze, Niigata Mag., 29, 773-791. Prefecture, Japan. Amer. Mineral., 52, 1785 (1960), The amygdale minerals in the 1794. - Tertiary lava of Ireland III . Regional distribu Ishida, S., Fujiyama, I., Hayashi, T., Noguchi, Y. tion. Mineral. Mag. 32, 503-527 . and Tomoda,Y. (1970),Geology and paleonto

長崎 県壱岐 島長 者原産 レビ沸 石およびエ りオ ン沸石

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壱 岐 島 長 者 原 の 新 第 三 紀 中 新 世 の 長 者源 層 の 火 山礫 岩,と くに そ の 中 の 変 質 玄 武 岩 礫 の 杏 仁 中 に は レ ビ沸

石,エリ オ ン沸 石,菱 沸 石,束 沸 石,灰 十 字 沸 石,ト ム ソ ン沸 石,ソ ー ダ沸 石 が巌 す る。 そ れ らの 中 で,レ ビ 沸 石 は本 邦 初 産 で あ り,エ リオ ン沸 石 と密接 に共 生 す るの で,こ の2種 類 の 沸 石 の 鉱 物 学 的性 質 ,共 生 関係 を 記 載 した 。 レビ 沸 石 は うす い板 状 結 晶(0001)で,貫 入 双 晶 を 示 す 。 エリオ ン沸 石 は レ ビ沸 石 と平 行 に 層 状 を な す が,せ ん い状 の 各結 晶 は レ ビン 沸 石 の(0001)面 に垂 直 に 発 達 す る 。 レ ビ沸石 は ω=1 .467で 複 屈 折 が極 め て 小 さい。X線 粉 末 デー タはAntrimの もの と一致 して い るが,薪 た に 指 数 づ け を行 っ た。 格 子恒 数 はa= 13.428±0.005A, c=22.662±0.008Aで あ る 。 単 結 晶X写 真 に よ る パ タ ー ン は 両 者 の 関 係 が レ ビ沸 石-エ リ オ ン 沸 石 エ ピ タ ク シ ー と レ ビ沸 石 の 双晶 と し て 説 明 さ れ る 。