著者

川崎 雅之 加藤 睦実 廣井 美邦 宮脇 律郎 横山 一己 重岡 昌子 鍵 裕之 砂川 一郎

出版者

一般社団法人日本鉱物科学会

雑誌

日本鉱物科学会年会講演要旨集 日本鉱物科学会 2012年年会

巻号頁・発行日

pp.61, 2012 (Released:2014-06-10)

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奈良県天川村洞川(どろがわ)にある五代松(ごよまつ)鉱山(接触交代鉱床)から黄色に着色した水晶が産出し、レモン水晶と称されて標本市場に流通している。この水晶は高過飽和条件下での樹枝状成長とそれに続く低過飽和条件下での層成長という二つの過程を経ていること、樹枝状水晶が種子となり、多面体水晶の形成を規制していることから、トラピッチェ・クオーツと呼べるものである。

著者

砂川 一郎

出版者

日本鉱物科学会

雑誌

鉱物学雜誌 (ISSN:04541146)

巻号頁・発行日

vol.3, no.6, pp.543-556_4, 1958-09-30 (Released:2010-02-08)

参考文献数

21

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On the basal plane of one crystal of hematite from an andesitic lava at Ayumikotan, Japan, three types of growth pyramids are described.First type, which is called the “tetrahedral” growth pyramid, consists of many closely spaced, thin, concentric, equi-lateral triangular growth layers. (Photo. 2, 5) On some of these growth pyramids spiral growth and interlacing can be observed. (Photo 5 a, b) On some growth pyramids the layers on one side of the triangular are produced into a peak suggesting the presence of an imperfect screw dislocation. (Photo. 5a) Measurement by multiple beam interferometry (Photo. 4) and fringes of equal chromatic order (Photo.3) show that thinnest growth layrs are 2.3Å thick (I/6 of the unit cell). Further details may be seen in Table 1.Second type is called the “triangular” growth layer. They are equi-lateral triangular growth layers on which no spirals have been observed. (Photo.7) It is suggested that growth took place by two-dimensional neucleation. The origin of the structure within the triangles and the linear arrangement of growth centres is described in the paper. (Photo.8, 9) At some distance from the growth triangles, a serrated structure, like sow-teeth, is developed. (Photo.6) This may also be seen around all growth pyramids of the first type. Measurements of thickness are shown in Table 3.In the third type of growth pyramids (Photo.10, 11) the thickness of the layersin different cases varies from 1 to 4 unit cell including thickness of 2n+1/2 unit cell (see Table4). These growth pyramids seem to be formed by screw dislocation, as there is a pit at the centre of each growth pyramid. The type of interlacing shown by these growth pyramids (Photo.11) suggests that polytypism may be present.From these observations it is deduced that this crystal has grown under the condition of comparatively high supersaturation.

著者

砂川 一郎

出版者

宝石学会(日本)

雑誌

宝石学会誌 (ISSN:03855090)

巻号頁・発行日

vol.2, no.4, pp.177-178, 1975-12-15 (Released:2017-01-16)

著者

砂川 一郎

出版者

地学団体研究会

雑誌

地球科学 (ISSN:03666611)

巻号頁・発行日

vol.1955, no.21, pp.23-30, 1955-02-25 (Released:2017-07-22)

著者

砂川 一郎

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.75, no.Special2, pp.55-62, 1980-08-30 (Released:2012-08-03)

参考文献数

19

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Although mineral crystals grow in nature under a broad spectrum of conditions, most natural crystallizations are considered to occur in solution phases, including both high temperature and aqueous solutions. When crystals grow from solution phases, the solidliquid interfaces are essentially smooth, where two dimensional layer-by-layer growth are expected. Judging from growth rates versus supersaturation relation, dislcoation controlled growth is expected for the supersaturation region below σ*, and hopper growth due to twodimensional nucleation mechanism for σ*-σ**, hereas unstable dendritic growth above σ**. Various inhomogeneities in crystals as well as surface microtopographs of crystal OfaOces may appear depending on the growth conditions. It was found on the basis of observati ons on these properties of natural crystals that in most natural crystallization, sprial growth and two-dimensional nucleation mechanisms are predominant mechanisms. This is true not only for crystallization in magma and hydrothermal solutions, but also for crystallization in metasomatic environments. For crystal growth mechanism in regional metamorphic environment, the so-called Ostwald ripening is suggested as principal mechanism, where interstitial solutions play an essential role, and thus the growth is similar to that from solution phases.

著者

砂川 一郎

出版者

宝石学会(日本)

雑誌

宝石学会誌 (ISSN:03855090)

巻号頁・発行日

vol.5, no.4, pp.169-171, 1978

著者

砂川 一郎

出版者

宝石学会(日本)

雑誌

宝石学会誌 (ISSN:03855090)

巻号頁・発行日

vol.5, no.4, pp.169-171, 1978-12-15 (Released:2017-01-16)

著者

砂川 一郎

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.96, no.7, pp.518-525, 1988-01-25 (Released:2009-11-12)

参考文献数

9

著者

砂川 一郎

出版者

日本結晶成長学会

雑誌

日本結晶成長学会誌 (ISSN:03856275)

巻号頁・発行日

vol.1, no.1, pp.18-19, 1974-11-01

著者

砂川 一郎

出版者

宝石学会(日本)

雑誌

宝石学会誌 (ISSN:03855090)

巻号頁・発行日

vol.9, no.2, pp.55-60, 1982

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Nambulite, LiNaMn_8Si_<10>O_<28>(OH)_2, and sugilite, (K, Na) C(H_2O), Na]_2 (Fe^<3+>, Na, Ti, Fe^<2+>)_2 (Li, Al, Fe^<3+>)_3 Si_<12>O_<30>, are two new minerals found and described for the first time in Japan. At the time of findings of the two minerals, no body imagined that these could be gem materials. But, recently, two minerals of gem quality have been found in Africa. Nambulite found at Kombat, Tsumeb, Nambia is deep red in colour and transparent, attaining 3cm in length, and cuttable as facet stones. Sugilite found in Wessels mine, Karahali manganese field, Cape Province, South Africa is violet in colour, and translucent, beautiful enough for cabochon cutting. This was at first reported as sogdianite, but later was identified as sugilite. Both are most unusual cases for new minerals found in Japan, and thus are introduced in this paper.

著者

砂川 一郎

出版者

日本結晶成長学会

雑誌

日本結晶成長学会誌 (ISSN:03856275)

巻号頁・発行日

vol.16, no.3, pp.207-208, 1990-03-25

著者

砂川 一郎 堀田 修三 沢田 秀穂

出版者

宝石学会(日本)

雑誌

宝石学会誌 (ISSN:03855090)

巻号頁・発行日

vol.10, no.1, pp.3-35, 1983

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Diamonds have been found occassionally in the tails of dressing of stream tin deposits in Phuke, Phangnga and Takua Pa Areas, South Thailand. From a geological point of view, the occurrence of diamond in Thailand implies unique and important meanings, since in Thailand kimberlites have not been found so far and there is no continental shield (craton) area in which most diamonds and kimberlites of the world have been found. In spite of this importance, no detailed studies on diamond crystals from Thailand have been made so far, although there have been four reports on their occurrences. In the present study, detailed surface microtopographic observations have been made of 15 diamond crystals, which were collected during the past 20 years by a gem dealer in Phangnga at a tin deposit in a small island, Dog Mai, off Phangnga and Phuket, South Thailand. Crystals are colourless, pale yellow, pale green and pale brown in colour, from 0.1 to over 0.7 ct in weight, and are very much rounded, showing rounded octahedral, tetrahedral, hexa-octahedral, dodecahedroidal and elongated dodecahedroidal morphologies (Fig. 3, 4, Table 1). The rounded morphology indicates that the crystals have suffered severe dissolution, most probably during the ascension of crystals in kimberlite magma, not during the transportation on the Earth's surface. Surface microtopographs representing various degrees of dissolution have been observed, which include rounded hexa-octahedral and dod-ecahedroidal faces (Fig. 12-16), circular disk depressions, often superimposed, and similar necklace-like patterns (Fig. 16-19), net work patterns (Fig. 20), all of which appear on rounded surfaces, and trigons appearing on flat {111} faces. Among these, trigons attract a particular attention. On the (111) faces of one of these crystals, all varieties of trigon morphologies are observed (Fig. 23, 25), which include trigons having opposite orientation to the triangle of the octahedral face (negative trigon, NT type), truncated NT (NT' type), hexagon (H type), and those having the same orientation as the triangle of the octahedral face (positive type, PT type), and truncated PT (PT' type). Both point-bottomed (P type) and flat-bottomed (F type) trigons are seen in a ratio of ca. 24 : 1. Trigons so far observed on {111} faces of natural diamond crystals are exclusively NT type and its deviation, and neither PT type trigons nor co-existence of both PT and NT types have been reported. Recent experimental studies have shown that trigons are etch pits and their orientations and morphologies change depending on temperature and oxygen fugacity (Fig. 21). Therefore, the co-existence of both PT and NT types on one octahedral face observed in the present study is very unique and suggests a rather peculiar condition under which diamonds from Thailand have experienced dissolution. The distributions of different types (Table 2), sizes (Table 3, Fig.26), and inclination angles of side faces (Table 4, Fig. 28) of ca. 8000 trigons occurring on flat table area and narrow terrace area on one (111) face are measured. The results are analysed, using a concept of surface reconstruction model proposed for Si etch pits by van Enckevort and Giling (1978) (Fig. 31, 33,34) and phase diagram of orientations of trigons (Fg. 21) by Yamaoka et al. (1980). Based on this analysis, the dissolution history of the crystal is suggested, in which the effect of change of oxygen fugacity is stressed (Fig.35). It is suggested that diamonds in Thailand came from kimberlite magma, whose chemistry was slightly different from that of kimberlites in other localities. This is in harmony with geological peculiarity of diamond occurrence in Thailand.