J. Japan. Assoc. Min. Petr. Econ. Geol. 72, 152-161, 1977.

KAERSUTITE, Ti-PARGASITE, AND PARGASITE FROM GABBROIC ROCK OF THE HOROMAN ULTRAMAFIC MASSIF, JAPAN

KIYOAKI NIIDA

Department of Geology and Mineralogy, Faculty of Science, Hokkaido University, Sapporo

Kaersutite, Ti-pargasite, and pargasite were found in gabbroic layers of the Horoman ultramafic massif. These amphiboles are regarded as primary minerals which crystallized from the residual liquid, and have a wide composition range in 100Mg/(Mg+Fe+Mn) from 87.5 to 68.2 and in SiO2 content from 41.19 to 44.50%. The TiO2 contents of kaersutite and Ti-pargasite vary continuously from 3.38 to 5.52%, whereas pargasite has 0.85% in TiO2. Composition ranges are examined for kaersutite, Ti-pargasite, and pargasite from other localities together with the Horoman amphiboles. Close relationship between kaersutite and pargasite is apparent. This relation may be accounted for by coupled substitution of Ti+2Fe2+=Mg+2AlV1 in the M(l)-M(3) sites as well as the Si ??Al substitu tion in the tetrahedral sites of Ti-rich amphibole. Hence, Ti-pargasite is regarded as a transi tional type between kaersutite and pargasite.

occurrence of druse pargasite in dacitic rocks INTRODUCTION was also reported by Matsumoto (1954). Kaersutite typically occurs in alkaline Definitions of kaersutite have been rocks (e.g. Washington and Wright, 1908; made by Aoki and Matsumoto (1959), Benson, 1940; Harumoto, 1933; Yagi, 1953; Wilkinson (1961), and Leake (1968). Wil Kerr, 1959; Aoki, 1959, 1963; Aoki and shire et al. (1971) and Wilshire and Trask Matsumoto, 1959; Mason, 1968; Prinz and (1971) gave a detailed description of occur Nehru, 1969; Wilshire et al., 1971; Grapes, rence of kaersutite and showed that it is 1975). Recently, many kaersutites in mafic produced by reaction between pargasite and and ultramafic inclusions have been reported basanitic magma. (e.g. Aoki, 1967, 1970; Le Maitre, 1969; Recently, Ti-pargasites in pyroxenite Best, 1970). Pargasite is a rare constitutent xenoliths from Lashine Volcano (Dawson of both metamorphic and igneous rocks, and Smith, 1973) and in wehrlites from the occurring in metamorphosed limestones and Mikabu Structural Belt (Tazaki and skarns (e.g. Deer et al., 1963), and in Inomata, 1974; Inomata and Tazaki, 1974) Inafic and ultramafic intrusions (e.g. Mac have been reported. Ti-pargasite, however, kenzie, 1960; Green, 1964; Nakamura, 1971). has not been defined exactly. Pargasite is also found in mafic and Small amounts of kaersutite, Ti-pargas ultramafic inclusions in basaltic rocks (e.g. ite, and pargasite have been recently found Varne, 1970; Wilshire et al., 1971; Aoki, in gabbroic rocks of the Horoman ultramafic 1971; Aoki and Shiba, 1973). A rare massif in the Hidaka Metamorphic Belt

(Manuscript received September 13, 1976) Kaersutite, Ti-pargasite, and pargasite from gabbroic rock 153

(Niida, 1976). In this paper, the present spinel, ilmenite, and titaniferous magnetite . writer gives descriptions of occurrence and This type is characterized by Ti-rich mine chemical analyses of these amphiboles from rals such as titaniferous diopside•`titani the Horoman massif and will discuss the ferous salite, kaerstutite, Ti-pargasite , and composition ranges of such amphiboles ilmenite. Type II gabbro (gabbro II) , together with those from other localities. which is more magnesian type, consists of

plagioclase, Ti-poor diopside, pargasite, and OCCURRENCE a small amount of olivine (FoS4). Mineral assemblages of all rock types of the Horo The Horoman ultramafic massif is man massif are summarized in Table 1. situated at the southwestern end of the Hidaka Metamorphic Belt and crops out Table 1 Mineral assemblages of the ultramafic over approximately 8X 10 km. Detailed and gabbroic facies of the Horoman descriptions of geology and petrography of ultramafic massif. the massif have been given by Igi (1953), Hunahashi and Igi (1956), Komatsu and Nochi (1966), and Niida (1974). The Horoman massif is representative of an "Alpine-type" peridotite intrusion with conspicuous layered structure, which is composed of dunite (D), lherzolite (L), plagioclase lherzolite (PL I and II), and a small amount of gabbro (GB I and II) and pyroxenite (OPX and CPX). Gabbroic O1: olivine Opx: orthopyroxene Il: ilmenite rocks occur as fine grained parts in plagio Sp: spinel Cpx: clinopyroxene Mt: magnetite clase lherzolite or as distinctive gabbroic P1: plagioclase Ti-parg: titaniferous pargasite Kaer: kaersutite Parg: pargasite layers which occur mainly in the Upper * diopside ** titaniferous diopside•`salite Zone of the massif. These gabbroic rocks *** salite-rcalcic augite () minor minerals are considered to have formed during the later stage of the fractional crystallization Ti-pargasite is usually found in the fine from the residual liquid which was trapped grained part of plagioclase lherzolite and in interstitially or as a pocket within solidified gabbro I, while kaersutite occurs only at the ultramafic parts (Niida, 1976). Recry margins of the latter. Both kaersutite and stallization textures are observed character Ti-pargasite occur usually as small grains istically in the ultramafic parts of the less than 0.5mm in size and are associated massif, whereas the gabbroic rocks show a with clinopyroxenes, olivines, and ilmenites primary texture (Niida, 1975). (Fig. 1). They show strong pleochroism There are at least two gabbroic rock from almost colourless to pale brown or types present. Type I gabbro (gabbro I), reddish brown. 2Vz is 84•K to 90•K. Pre which is the most common, contains plagio viously, these amphiboles of the Horoman clase, titaniferous diopside-titaniferous gabbroic rocks have been described as a pale salite, olivine (Fo83-64),kaerstutite and Ti brown hornblende by Igi (1953) and Niida pargasite, with small amounts of green (1974). 154 K. Niida

CHEMICAL COMPOSITION

Chemical compositions of kaersutite, Ti

pargasite, and pargasite in the gabbroic rocks were analyzed by electronprobe

microanalyzer (JEOL: JXA-5A) at the

Geological Survey of Japan. Operation

conditions were 15 kv accelerating potential

and 0.02-0.03 ƒÊA specimen current. The

electron beam diameter was kept at about 5

microns. The data were computed into

oxide percentages using a correction program

Fig. 1 Photomicrograph of kaersutite (K) asso written by Okumura and Kawachi (1971) ciated with Ti-diopside (cpx), olivine (ol), for quantitative EPMA analyses, which plagioclase (pl), and accessory ilmenite. A marginal part of the gabbro I (sample is essentially the same method as that of Apk 63016 b) from the western ridge of Sweatman and Long (1969). Stuctural Apoi-dake, Horoman. formulae of the amphibole analyses were

calculated using a program developed by

Kawachi (1971).

Five kaersutites, fourteen Ti-pargasites,

and two pargasites were analyzed. The

results together with structural formulae

calculated on the basis of O=23 are listed

in Table 2 in order of decreasing Mg: Fe

ratio.

The Horoman Ti-rich pargasite contains

up to 5.5wt% in TiO2,. The Ti-rich

pargasite from the fine grained parts of the

plagioclase lherzolite has TiO2 contents Fig. 2 Photomicrograph of pargasite (P) associated ranging from 3.38 to 4.08%, and in the with diopisde (cpx), olivine (ol), and pla gabbro I (GB I) from 3.78 to 5.52%. The gioclase (pl). A layer of the gabbro II Ti-poor pargasite from the gabro II (GB (sample Apk 82811 a) from the western ridge of Apoi-dake, Horoman. II) contains only 0.85% TiO2. According

to Aoki and Matsumoto (1959) and Aoki

Ti-poor pargasite occurs in the layers (1963) kaersutite contains more than 5.0 of gabbro II. The Ti-poor pargasite is as wt% TiO2. Leake (1968) called the

sociated with Ti-poor diopside and olivine mineral containing more than 0.5 Ti atoms

(Fig. 2). The pargasite has a maximum per formula unit kaersutite. Taking these

grain size of 1.0mm, and shows weak definitions into account, some of the

pleochroism from colourless to pale green. Horoman Ti-rich pargasite clearly corres

2Vz is 83•K to 92•K. pond to kaersutite (Nos. Kl-5 in Table 2). Atomic ratios of 100Mg/(Mg+Fe+Mn)

of these amphiboles vary continuously from Kaersutite, Ti-pargasite, and pargasite from gabbroic rock 155

87.5 to 68.2. Numbers of Si atoms of the Horoman kaersutite and Ti-pargasite COMPOSITION RANGES OF KAERSU range from 5.96 to 6.24, and those of the TITE, Ti-PARGASITE, AND PARGASITE pargasite vary from 6.32 to 6.36. However, Relations between kaersutite and par the variation in Na+K content of these gasite have been discussed by Wilkinson amphiboles is limited to a range from 0.9 (1961), Wilshire et al. (1971), and Wilshire to 1.1. Al atoms in tetrahedral sites are and Trask (1971). Wilkinson (1961) sug between 1.64 to 2.04. gested that kaersutite corresponds to a No signs of compositional zoning are titaniferous pargasite with part of the Mg seen in any of the grains, though there is replaced by Fee,, and gave the general a wide compositional variations between formula of (Na, K, Ca)2-3(Mg3 Fe2+)TiAlIV2 kaersutite and pargasite from different Si6O23(OH). Such relation has been also gabbroic rocks. repeated by Aoki (1963, 1970). Leake (1968) pointed that Ti-rich amphibole falls

Table 2 EPMA analyses and structural formulae for kaersutite, Ti-pargasite, and pargasite from the Horoman ultramafic massif.

* total iron expressed as FeO PLI: plagioclase lherzolite I GBI: gabbro I ** Fe2+ PLII: plagioclase lherzolite II GBII: gabbro II *** 100Mg/(Mg+Fe+Mn) 156 K. Niida

Table 2 (continued)

into the pargasite-hastingsite range because sutite and pargasite. According to Niida they have Si below 6.25 and Ca+Na+K (1976), pargasite crystallized from residual equal to 2.50 or above. The formation of liquid at the middle stage of crystallization kaersutite by the reaction between of the ultramafic massif, whereas kaersutite pargasite and basanitic magma has been crystallized at the later stage. It is reported by Wilshire et al. (1971). All these noteworthy that the Horoman Ti-pargasite studies show an intimate genetical relation occurs as a transitional type between the ship between kaersutite and pargasite. pargasite and kaersutite. Recently, Ti-pargasites have been found Chemical relations between 187 kaer in alkalic pyroxenite xenoliths from the sutite, Ti-pargasite, and pargasite analyses

Lashine Volcano (Dawson and Smith, 1973) from various localities in the world and those and in wehrlites from the Mikabu zone in from the Horoman massif are illustrated in Japan (Inomata and Tazaki, 1974; Tazaki Figs. 3 to 5. In Fig. 3 the analyses plot and Inomata, 1974). near the pargasite position of AlIV=2.0 and

Subsequent to Wilshire et al. (1971), Na+K=1.0. Kaersutites mainly fall the Horoman amphiboles show a geneti into the region of AlIV•†2.0. Ti-pargasite cally closed relationship between kaer and pargasite, on the other hand, fall into Kaersutite, Ti-pargasite, and pargasite from gabbroic rock 157

Fig. 3 AlIv v.s. Na+K plots of kaersutite, Ti-pargasite, and pargasite. SOURCE OF DATA (*see Leake, 1968; **see Deer et al., 1963) KAERSUTITE (95 analyses); Schneider (1891)*, Brogger (1898)*, Flett (1900)**, Harrington (1903) *, Washington and Wright (1908), Galkin (1910)*, Bancroft and Howard (1923)*, Kaiser (1925)*, Billings (1928)*, Gossner and Spielberger (1929)*, Kunitz (1930)*, Parsons (1930)*, Harumoto (1933), Kawano (1934)**, Tomita (1934)**, Benson (1939)*, Campbell and Schenk (1950)**, Vincent (1953)**, Yagi (1955), Naidu (1954)*, Aoki and Matsumoto (1959), Brousse (1961)* Wilkinson (1961), Aoki (1963), Fabrics (1963),* Howie (1963)*, Gutberlett and Hocherholz (1965)*, Aoki (1967), Mason (1968), Le Maitre (1969), Prinz and Nehru (1969), Aoki (1970), Best (1970), Wilshire et al. (1971), Grapes (1975), Niida (1976). Ti-PARGASITE (38 analyses); Dawson and Smith (1973), Inomata and Tazaki (1974), Tazaki and Inomata (1974), Niida (1976). PARGASITE (54 analyses); Eakins (1890)*, Penfield and Stanley (1907)*, Laitakari (1921)**,Eckerman (1922)**, Mangusson (1930)**, Parsons (1930)*, Erdmannsdorffer (1937)*, Koritnig (1940)**, Larsen (1942)*, Davidson (1943)*, Lundogardh (1943)*, Korjinski (1945)*, Hallimond (1947)**, Sameshima (1949)*, Matsumoto (1954), Rosenzweig and Watson (1954)**, Serdiuchenko (1954)*, Korjinski (1956)*, Yen (1959)*, Bloxam and Allen (1960)*, Gillberg (1960)**, Mackenzie (1960), Tomita (1962)*, Matsumoto (1963)*, O'Hara and Mercy (1963)*, Green (1964), Onuki (1964)*, Varne (1970), Aoki (1971), Nakamura (1971), Wilshire et al. (1971), Aoki and Shiba (1973), Niida (1976). the region of AlIV 2.0. Leake's (1968) diagram (Fig. 4). This figure The Ca+Na+K content of kaersutite, emphasizes that most analyses of kaersutite Ti-pargasite, and pargasite is mostly limited have a low Si content (Si•…6.00), whereas to a range from 2.50 to 3.00, as shown in Ti-pargasite and pargasite have Si contents 158 K. Niida

Fig. 4 Plots of Si and Ca+Na+K of kaersutite, Ti-pargasite, and pargasite. in excess of 6.00 atoms per formula unit. kaersutite, as mentioned by Wilkinson Generally, these amphiboles are rich in total (1961). Al, and have also high Alvl content up to The Ti-total Fe relation shows a about 1.00. The AlvI content of pargasite positive correlation among these amphiboles; is especially high. Ti content increases with increase of total Mg+total Fe content of these amphi Fe content. Similarly, Mg and A1vTshow boles ranges from 3.5 to 4.5 atoms per a positive correlation. On the other hand, formula unit in pargasite, 3.0 to 4.0 in Ti the Ti-AlVI relation is negative; e.g. the pargasite, and 2.0 to 3.5 in kaerustite, and analyses of kaersutite, Ti-pargasite, and indicates the presence of Mg ?? Fe2+ substitu pargasite from the peridotite inclusions in tion in the transition from pargasite to the Dish Hill basanite (Wilshire et al., 1971) Kaersutite, Ti-pargasite, and pargasite from gabbroic rock 159

Fig. 5 Total Fe+Ti v.s. Mg+AlVI relation of kaersutite, Ti-pargasite, and pargasite.

and the gabbroic rocks of the Horoman amphiboles. massif. Therefore, Ti-pargasite is expected to As demonstrated in a summarized be found in many other rocks carrying diagram of total Fe+Ti versus Mg+AlVI kaersutite.

(Fig. 5), the compositions of kaersutite, Ti

pargasite, and pargasite mainly plot along ACKNOWLEDGEMENTS the line of total Fe+Ti+Mg+AlVI=5. The The present writer wishes to express his kaersutite have higher total Fe+Ti (•†l.5) sincere thanks to Prof. Y. Katsui and Drs. and lower Mg+Alv1 (•…3.5), whereas the K. Onuma and R.H. Grapes of the Hokkaido pargasites show the reverse relation. As University for kind advice and critical read expected Ti-pargasite plots are transitional ing of the manuscript. Special thanks are between kaersutite and pargasite. expressed to Drs. S. Igi, H. Sato, T. Soya, Substitution of Ti-rich amphibole has and K. Okumura of the Geological Survey of not been enough discussed. Shido (1958) Japan for their kind assistance with EPMA proposed Ti•E2Al ?? Mg • 2Si for titano analysis and computer programming. amphibole substitution. It is evident from Fig. 5 that the substitution of Ti+2Fe2+ REFERENCES ?? Mg+2AlVI in the M(l)-M(3) sites as well Aoki, K. (1959), Petrology of alkali rocks of the as Si-Al in tetrahedral sites takes place Iki Islands and Higashi-matsuura district,

between kaersutite and pargasite. As Japan. Sci. Rep. Tohoku Univ., Ser. 3, 6, 261-310. mentioned above, Ti-pargasite is regarded Aoki, K. and Matsumoto, H. (1959), On kaersutite as a transitional type between above two from the Iki Island, Nagasaki Prefecture. J. 160 K. Niida

Japan. Assoc. Min. Pety. Econ. Geol., 43, 248- McGraw-Hill Bock Co., N. Y., p. 442. 253 (in Japanese). Komatsu, M. and Nochi, M. (1966). Ultrabasic Aoki, K. (1963), The kaersutites and oxykaersutites rocks in Hidaka metamorphic belt, Hokkaido, from alkalic rocks of Japan and surrounding Japan. I. Mode of occurrence of the Horo area. Jour. Petrol., 4, 198-210. man ultrabasic rocks. Earth Science, 20, 99- Aoki, K. (1967), Kaersutite pyroxenite inclusion 108 (in Japanese with English abstract). in trachybasalt from Takenotsuji, Iki Island. Leake, B. E. (1968), A catalog of analyzed calci J. Japan. Assoc. Min. Pety. Econ. Geol., 57, ferous and subcalciferous amphiboles together 111-119 (in Japanese with English abstract). with their nomenclature and associated min Aoki, K. (1970), Petrology of kaersutite-bearing erals. Geol. Soc. Amer., Spec. Pap. 98, 1-210. ultramafic and mafic inclusions in Iki Island, Le Maitre, R. W. (1969). Kaersutite-bearing plu Japan. Contr. Mineral. Petrol., 25, 270-283. tonic xenoliths from Tristan da Cunha, South Aoki, K. (1971), Petrology of mafic inclusions from Atlantic. Min. Mag., 37, 185-197. Itinomegata, Japan. Contr. Mineral. Petrol., MacKenzie, D. B. (1960). High temperature alpine 30, 314-331. type peridotite from Venezuela. Bull. Geol. Aoki, K. and Shiba, I. (1973), Pargasites in lher Soc. Amer., 71, 303-318. zolite and websterite inclusions from Itinome Mason, B. (1968), Kaersutite from San Carlos, gata, Japan. J. Japan. Assoc. Min. Petr. Econ. Arizona, with comments on the paragenesis Geol., 68, 303-310. of this mineral. Min. Mag., 36,997-1002. Benson, W. N. (1940), Kaersutite and other brown Matsumoto, H. (1954), Pargasite from Ishigami amphiboles in the Cainozoic igneous rocks of yama, Kumamoto Prefecture. Kumamoto the Dunedin district. Trans. Roy. Soc. N. Z., Jour. Sci., 4, 93-95. 69, 283-308. Nakamura, Y. (1971), Petrology of the Toba Best, M.G. (1970), Kaersutite-peridotite inclusions ultrabasic complex, Mie Prefecture, central and kindred megacrysts in basanitic lavas, Japan. J. Fac. Sci., Univ. Tokyo, Sec. II, 18, Grand Canyon, Arizona. Contr. Mineral. 1-51. Petrol., 27, 25-44. Niida, K. (1974), Structure of the Horoman Dawson, J. B. and Smith, J. V. (1973), Alkalic ultramafic massif of the Hidaka metamorphic pyroxenite xenoliths from the Lashine belt in Hokkaido, Japan. Jour. Geol. Soc. Volcano, northern Tanzania. Jour. Petrol., Japan, 80, 31-44. 14, 113-131. Niida, K. (1975), Textures and olivine fabrics of Deer, W. A., Howie, R. A., and Zussman, J. (1963), the Horoman ultramafic rocks , Japan. J. Rock forming minerals. Vol. 2, 263-327. Japan. Assoc. Min. Petr. Econ. Geol., 70, Grapes, R. H. (1975), Petrology of the Blue Mountain 265-285. complex, Marlborough, New Zealand. Jour. Niida, K. (1976), Petrology of the Horoman ultra Petrol., 16, 371-428. mafic rocks in the Hidaka metamorphic belt, Green, D. H. (1964), The petrogenesis of the high Hokkaido, Japan. Sc. D. thesis of Hokkaido temperature peridotite intrusion in Lizard Univ. area, Cornwall. Jour. Petrol., 5, 134-188. Prinz, M. and Nehru , C. E. (1969), Comments on Harumoto, A. (1933), On the kaersutite and "Kaersutite from San Carlos, Arizona, with pigeonite found in the volcanic ejecta, Utsuryo comments on the paragenesis of this mineral" Island. Chikyu (The Globe), 19, 96-110 (in by Brian Mason. Min. Mag., 37, 333-337. Japanese). Shido, F. (1958), Plutonic and metamorphic rocks Hunahashi, M. and Igi, S. (1956), Explanatory of the Nakoso and Iritono districts in the text of the geological map of Japan "Horo central Abukuma Plateau. J. Fac. Sci. Univ. izumi" (scale 1:50,000). Geol. Surv. Japan, Tokyo, Sec. II, 11, 131-217. (in Japanese with English abstract). Sweatman, T. R. and Long, J. V . P. (1969), Quan Igi, S. (1953), Petrographical studies on the peri titative electronprobe microanalysis of rock dotite in the Horoman region at the southern forming minerals. Jour. Petrol ., 10, 332-379. end of the Hidaka mountain range , Hokkaido. Tazaki, K. and Inomata, M. (1974), Phlogopites and Jour. Geol. Soc. Japan, 59, 111-121 (in coexisting pargasites in wehrlite from nor Japanese with English abstract). thern Kanto mountains, central Japan. Pap. Inomata, M. and Tazaki, K . (1974), Phlogopite and Inst. Thermal Spring Research, Okayama Ti-pargasite-bearing ultramafic rocks from the Univ., 43, 1-13 (in Japanese with English Mikabu zone, central]Japan. J. Japan . Assoc. abstract). Min. Pety. Econ. Geol., 69, 205-214 . Varne, R. (1970), Hornblende lherzolite and the Kerr, P. F. (1959) , Optical Mineralogy, 3rd Ed., upper mantle. Contr. Mineral . Petrol., 27, 45 Kaersutite, Ti-pargasite, and pargasite from gabbroic rock 161

51. phlogopite in peridotite inclusions, Dish Hill, Washington, H. S. and Wright, F. E. (1908), On California. Amer. Min., 56, 240-255. kaersutite from Linosa and Greenland. Amer. Wilshire, H. G., Calk, L. C., and Schwarzman, E. C. Jour. Sci., 26, 187-211. (1971), Kaersutite-a product of reaction Wilkinson, J. F. G. (1961), Some aspects of the between pargasite and basanite at Dish Hill, calciferous amphiboles, oxyhornblende, kaer California. Earth Planet. Sci. Lett., 10, 281- sutite, and barkevikite. Amer. Min., 46, 340- 284. 354. Yagi, K. (1953), Petrochemical studies on the Wilshire, H. G. and Trask, N. J. (1971), Structural alkalic rocks of the Morotu district, Sakhalin. and textural relationships of amphibole and Bull. Geol. Soc. Amer., 64, 769-810.

幌満超苦鉄質岩体のはんれい岩相中のケルスー ト閃石 ・ チタンパーガス閃石およびパーガス閃石

新 井 田 清 信

幌 満超 苦 鉄 質岩 体 の は ん れ い岩 相 中 に は ケ ル ス ー ト閃石 ・チ タンパ ー ガ ス閃 石 お よび パ ー ガ ス閃 石が 含 まれ て い る。 にの うち,チ タ ンに 富 む パ ー ガス 閃石 は斜 長 石 レル ゾ ラ イ トの細 粒部 お よび は んれ い 岩Iに 認 め られ,ケ ル スー ト閃石 は はん れ い 岩Iの 周 縁 部 に 限 って 産 出 す る。一 方,パ ー ガ ス閃 石 は よ り早期 相 と考 え られ るはん れ い岩IIに 含 まれ る。 これ らの 角 閃石 は い ずれ も幌 満岩 体 の残 液 か ら晶出 した初 生鉱 物 で あ る。 これ らの うちケ ル スー ト閃石5個,チ タ ンパ ー ガ ス閃石14個,パ ー ガ ス閃 石2個 をEPMAに よ り化学 分 析 し た とこ ろ,著 し い組成 変 化 が 認 め られ た。 幌 満岩 体 の 角 閃 石 を含 む 世 界 各 地 の これ らの角 閃 石187個 につ い て 化 学組 成 を検 討 し た。 その結 果,ケ ル ス ー ト閃石とパ ー ガ ス閃 石 の 間 に は, 4配 位 の 位置 で のSi〓Al置 換 と と もに, M(1)～M(3)サ イ トでTi+2Fe2+〓 Mg+2AlVIの 置 換 が お こな わ れ て い る こ とが 明 らか とな っ た。 ま た,チ タ ンパ ー ガ ス閃 石 はパ ー ガス 閃石 とケ ル スー ト閃石の 間 の 漸移 型 と考 え られ る。 従 って,チ タン パ ー ガ ス閃 石 は,将 来,ケ ル ス ー ト閃石 を含む 他 の 岩 石 に も多 く見発 され るで あ ろ う。