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Tanakamiyama A Classic Japanese Pegmatite District

anakamiyama, 太神山, sometimes written 田上山 2002). The literature of the Tanakami-fudo temple (Shu- (Mt. Tanakami; roughly 600 meters in elevation), gendo sect), which was built in 859 on the top of Tanakami- T lies just east of the city of Kyoto, on the southern yama, suggests that the name of this mountain, 太神 (tana end of Lake Biwa, in Shiga Prefecture (fig. 3). It is part of + kami = great + god), is related to Amaterasu-omikami, a large area of eroded hills that is underlain by Tanakami the sun goddess of Japanese mythology (Ashkenazi 2008). A Granite (figs. 1 and 2). Known as the Tanakami region or contrary etymology simply Tanakami, it is one of the most important specimen- JOHN RAKOVAn is found in Omi Yochi producing pegmatite districts in Japan, along with the Hiru- Department of Geology Shiryaku (1734) by kawa area in Gifu Prefecture and the Fukushima district, Miami University Tokikiyo Samukawa, Ishikawa Prefecture (Nambu 1970). Tanakami is probably Oxford, Ohio 45056 a comprehensive ge- most noteworthy for its production of fine topaz crystals [email protected] ography of Omi and as the type locality for masutomilite (a manganese- Province. This states lithium mica). MIEKO ONO that tanakami, 田上 Recognized as a classic Japanese mineral locality, Tanaka- Department of German, Russian, (= rice field + above), miyama is also noted for a long history of cultural and envi- and East Asian Languages was originally tani- ronmental significance. In a waka poem (the classical style of Miami University kami, 谷上(valley + Japanese verse that predates haiku) in the book Minamoto no Oxford, Ohio 45056 above), as is writ- Toshiyori Kashu about Tanakamiyama (ca. 1128), Kumorina- ten in the Nihongi ki yuzukuhiomo mitsurukana, kore kaminoyamano shirushi- CARL A. FRANCIS (ad 720 the earli- naruran translates as “Glorious sunset! This must be a sign of Mineralogical Museum est official history a holy mountain.” This reference alludes to the sacred stature Harvard University of Japan). Thus, of the mountain to the Shugendo religion, which incor- Cambridge, Massachusetts 02138 the pronunciation porates an ascetic, mountain-dwelling lifestyle (Kasahara­ [email protected] changed over time

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Figure 1 (left page). Northwest view from Tanakamiyama (May Figure 2 (top). Geological map of the Tanakamiyama area (red 2005). The southern end of Lake Biwa and the city of Otsu can box in fig. 5). The partial ring of Cretaceous granites (in red), be seen in the background. Note the highly weathered granite including the Tanakami Granite, indicates the location of the exposure in foreground. Biwa Caldera.

Figure 3 (left). Map of Japan, prepared by William Besse.

from tani-kami, 谷上, through ta-no-kami, 田上, to ta-na- kami, 田上.* For more worldly matters, the Tanakami Mineral Muse- um, located in Tanakamieda-cho, Otsu (by appointment only, phone 077-5460-163 or 077-546-1921), houses a small collection of local minerals, but many finer specimens can be seen in larger museum collections around Japan and in older mineral collections abroad.

*A widely held view, however, is that tanakami, 田上, actually means 田神 (rice field + god) (Yanagida 1975; Wada 1994).

Dr. John Rakovan, an executive editor of Rocks & Minerals, is a professor of mineralogy and geochemistry at Miami Univer- sity, Oxford, Ohio. Dr. Mieko Ono is a professor of Japanese linguistics at Miami University. Dr. Carl Francis, a consulting editor of Rocks & Minerals, is the curator of the Harvard Mineralogical Museum.

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Japanese geology (Kunz 1920). He was a major force in the modernization of mining in Japan, and he amassed what still remains the finest collection of Japanese minerals in existence. After his death, this collection of more than 3,700 specimens was acquired by Mitsubishi Mining Corpora- tion and is currently on display at the Ikuno Mine Mineral Museum (Rakovan 2005a). Many of these specimens are depicted in Wada’s Minerals of Japan (1904).

Geology Tanakamiyama is located on the main Japanese island of Honshu (fig. 3). The Inner (northern) Zone of southwest Honshu is divided geologically into the Ryoke, Sanyo, and Sanin belts (fig. 5), which differ in age of deposition, degree of metamorphism, and nature of mineralization (Yuhara, Kagami, and Nagao 2000). Tanakamiyama lies in the Sanyo Belt (Kohno, Nakano, and Shimobayasi 2009), near the boundary of the metamorphic Ryoke Belt, both of which experienced extensive felsic igneous activity during the Cretaceous Period (Hayama and Tainosho 2000; Yuhara, Kagami, and Nagao 2000). The exposure of the Tanakami Granite pluton measures 20 kilometers east-west and 8 kilometers north-south. It is the largest and southernmost of several igneous intrusions that form a geographic ring of granitic exposures associ- ated with the formation of the Biwa-ko Caldera (Sawada et al. 1994). Most of these intrusions are hosted by Juras- sic sedimentary rocks of the Tamba accretionary complex Figure 4. Prof. Tsunashiro Wada. (Hashimoto et al. 2000). The pluton is composed of biotite granite with high silica and alkali contents (73.3–76.7% SiO ; 8.0–8.9% Na O+K O) and Rb/Sr ratios. The granite Harvard Collection 2 2 2 In the United States one collection that is rich in speci- is rich in rare-earth elements (REE), with increasingly high mens from this location is that of the Harvard Mineral- concentrations of fluorine and lithium toward the core of ogical Museum (figs. 6–18). Notable specimens include the pluton (Ishihara, Nakano, and Terashima 2005). several exceptional topaz crystals, numerous fine orthoclase Interestingly, the Tanakami Granite, and its treasure trove crystals—many in association with quartz and albite—and of fine minerals, was formed long before the Japan archi- an outstanding gem crystal of aquamarine, one of the finest Figure 5. Regional geological map of southwest Japan. MTD = that we have seen from Japan. Most of Harvard’s specimens Median Tectonic Line; ISTL = Itoigawa-Shizuoka Tectonic Line; were obtained at the turn of the last century, including the red rectangle around Kyoto and Tanakamiyama indicates several specimens sent to Harvard by Dr. Tsunashiro Wada the area shown in figure 2 (modified from Yuhara 2000). (fig. 4). This collection is on dis- play at the Karl E. Limper Geol- ogy Museum at Miami University in Oxford, Ohio, until December 2010. Wada (1856–1920) is consid- ered the father of modern min- eralogy and geology in Japan. He was the first Western-trained mineralogist (in part by German geologist Heinrich Edmund Nau- mann), the first Japanese professor of mineralogy at Tokyo Univer- sity, and the first director of the Geological Survey of Japan; these are but a few of the seminal posi- tions that Wada held in the field of

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Figure 6 (left). Beryl (var. aquamarine), 6.2 cm high; highly etched. Harvard specimen 88294, Terry Huizing photo. Figure 7 (center). Topaz and orthoclase, 7 cm high. It has been suggested that the large red inclusion is a garnet; however, the authors are skeptical. Harvard specimen 103077, Terry Huizing photo. Figure 8 (right). Microcline, 8 cm high, exhibiting the Baveno twin law. Harvard specimen 84699, Terry Huizing photo.

pelago existed. Japan is a tectonic arc that has been evolving meters at its widest part. The pocket yielded numerous crys- throughout the Phanerozoic. It is the result of subduction of tals including a very large topaz (weighing 6 kilograms) and the ancient Pacific seafloor underneath the eastern edge of a doubly terminated crystal of smoky quartz just over 30 cm the Eurasian Plate (Taira 2001). The complex tectonic geom- in length (Obayoshi 2000). etry of the Japanese islands involves the convergence of four distinct tectonic plates, including the North American Plate Mineralogy (locally called the Okhotsk Plate) on which the United States The mineralogy of the Tanakamiyama pegmatites is sim- is also located. The island arc separated from the mainland ple, as is common in NYF-type pegmatites. Dominant relatively recently, with the opening of the Japan Sea back minerals include microcline, albite, quartz, beryl (aquama- arc basin, about 15 million years ago. Throughout the rine), topaz, muscovite, zinnwaldite, and masutomilite. A Cretaceous Period, oblique subduction of the northward- complete list of minerals from this location is given in the moving Kula-Pacific Ridge along the eastern margin of the table below. Eurasian Plate generated a large number of granitic intru- Tanakamiyama is most famous for its superb topaz speci- sions (Kinoshita 1999), including the granites and granitic mens. The first description of what was probably topaz pegmatites of Tanakamiyama and the Hirukawa district of from Tanakamiyama was made by Sekitei Kinouchi (birth Gifu Prefecture. A rubidium-strontium whole rock isochron age of 79.5 Minerals reported from Tanakamiyama. Compilation ± 9.0 million years with an initial 87Sr/86Sr ratio of 0.70951 from Obayoshi (2002) and Mindat (2008). ± 0.00037 (Sawada et al. 1994) provides the time of intru- Albite Hübnerite Quartz (smoky sion of the Tanakami Granite (Morioka, Tainosho, and Allanite-(Ce) Lazulite quartz, agate) Kagami 2000). Almandine Masutomilite* Ralstonite? Beryl (var. Microcline Rutile Syngenetic, miarolitic NYF*-type pegmatites are associ- aquamarine) Milarite† Samarskite-(Y) ated with the Tanakami Granite as irregular, crystal-lined Biotite Molybdenite Schorl pockets with thin rinds of graphic granite. This is a similar Cassiterite Monazite-(Ce) Siderite Columbite Montmorillonite Sphalerite style of occurrence to other miarolitic NYF-type pegmatites Euxenite-(Y) Muscovite Topaz such as those found in the Conway Granite in New Hamp- Fergusonite-(Y) Opal (var. hyalite) Vivianite shire and the Pikes Peak Batholith in Colorado (London Fluorite Orthoclase Wolframite Gadolinite-(Y) Pyrite Yttrotantalite-(Y) 2008; Rakovan 2008). One of the largest miarolitic cavi- Galena Pyrolusite Zinnwaldite ties recorded from Tanakamiyama was discovered in 1974 Heulandite Pyrrhotite Zircon by Kazuo Nakazawa. It measured 6.5 meters long and 1.6 Hingganite-(Y)

*Type location. †New addition (this article). *Niobium-yttrium-fluorine.

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Figure 11 (top). Muscovite and topaz, 10 cm across. Harvard specimen 85888, Terry Huizing photo.

Figure 9 (top). Quartz with hoppered faces, 5.5 cm high. Har- Figure 12 (above). Topaz, quartz, and albite, 6.5 cm high. Note vard specimen 83020, Terry Huizing photo. rounded growth hillocks on large topaz face. Harvard specimen 103075, Terry Huizing photo. Figure 10 (above). Microcline (var. amazonite), 9 cm across. Harvard specimen 131062, Terry Huizing photo. Shiga Prefecture.* On a tour to inspect erosion control of the Tanakamiyama area he spotted a “beautiful transpar- name Shigesato Kinouchi, 1724–1808), a distinguished min- ent” stone measuring 6 × 9 cm. Koteda gave the crystal to eral collector of the Edo period (1603–1868). In his book Edmund Naumann and Tsunashiro Wada at Tokyo Univer- Unkonshi (vol. 1, 1773; vol. 2, 1779; and addendum, 1801) sity who identified it as topaz. Koteda’s topaz is mentioned a topazlike mineral called hari (crystal/glass) is said to in the oldest mineralogy textbook in Japan, Hampo-kinseki- “resemble crystals but not in the shape of hexagon. Highly lucid … occasionally found in Hakuriyama in Tanakami, *In a contrary account, according to Meiji Jibutsu Kigen (1908) by Kendo Ishii, topaz was first found in Japan by Kanbei Takagi in 1870 on Naegi- Omi.” What may be the first officially recognized topaz yama in Mino (Gifu Prefecture). Kanbei made a fortune in the mineral trade was found in 1873 by Yasusada Koteda, then governor of and was locally nicknamed “Topaz Kanbei.”

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rayakushi-zen (1878, T. Wada, ed.). Extensive descriptions and goniometric measurements and numerous drawings and pictures of topaz from Tanakamiyama are presented in Minerals of Japan (Wada 1904), including the specimen that Wada considered the best from this location. A color picture of this specimen, currently on display at the Ikuno Museum in Ikuno, Japan, is shown in figure 3 of the Word to the Wise column titled “NYF-type Pegmatite” (Rakovan 2008). A recent addition to the list of known minerals from the pegmatites of Tanakami is milarite, a hydrated potassium calcium aluminum beryllium silicate of the osumilite group. Hexagonal prisms of milarite to 1 mm long are found in association with microcline, schorl, and quartz. They were identified by unit cell refinement (a = 10.395, b = 10.395, c = 13.817, α = 90o, β = 90o, γ = 120o) from single-crystal X-ray diffraction data collected at Miami University. The specimen was loaned for study by Alfredo Petrov and has subsequently been donated to the Masutomi Museum in Kyoto, Japan. It has an original A. E. Foote label attached to the back of the specimen (fig. 21) and was probably brought to the United States sometime in the late nineteenth century.

Historical and Cultural Significance The cultural history and significance of Tanakamiyama are very interesting and are likely related to the discovery of pegmatites. Tanakami (sometimes spelled Tanokami) was known for its beautiful hinoki forests (Japanese cypress), and several waka poems about the area are found in the Manyoshu, the oldest existing collection of Japanese poetry, written mostly between the sixth and eighth centuries. One waka poem (No. 50 in the Manyoshu), written by a worker involved in the construction of Fujiwara-no-miya (the palace of the imperial capital of Japan between 694 and 710), described the transport of hinoki for the palace from Tanakami via the Uji River. From the end of the fifth

Figure 14 (top). Topaz, 5 cm across. Harvard specimen 103076, Terry Huizing photo.

Figure 15 (above). Topaz, 4.5 cm high, waterworn. Harvard specimen 139366, Terry Huizing photo.

century ad, the Japanese imperial (Yamato) court started extensive logging of the Tanakami area for the building of palaces, such as Fujiwara-no-miya, and temples in Kyoto, Nara, Otsu, and elsewhere in the region. Other well-known buildings constructed from Tanakami lumber include the Todai-ji temple in Nara City (ca. 752) and Ishiyama-dera (ca. 749), the temple where Shikibu Murasaki is believed to have begun writing the Tale of Genji in 1004 (a famous court story of the Heian period, considered by many scholars to be the world’s first novel). Figure 13. Muscovite and microcline, 7 cm across. Harvard Overlogging deforested the Tanakami area, resulting in specimen 86940, Terry Huizing photo. accelerated weathering and serious erosion problems that

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Figure 18 (top). Microcline and albite, 7 cm high. Harvard speci- men 84704, Terry Huizing photo.

Figure 19 (above). Microcline, schorl, quartz, and milarite (small crystals in 1–2-cm radius around the largest schorl crys- tal); specimen about 6 cm across. Masutomi Museum (Kyoto) specimen, John Rakovan photo. Figure 16 (top). Topaz, 4 cm high, etched. Harvard specimen 85885, Terry Huizing photo. ties employed the Dutch engineer Johannis de Rijke to help Figure 17 (above). Microcline, exhibiting the Baveno twin law, with erosion control in Tanakami (Takebayashi 2004). He smoky quartz, and albite, 8 cm high. Harvard specimen 84695, started a program of reforestation that continues today, and Terry Huizing photo. the area is now mostly recovered; however, for more than a millennium Tanakamiyama and surrounding hills were adversely affected settlements along the nearby Seta and Uji bare. For centuries during its exposure, the Tanakami Gran- rivers from Otsu to Osaka Bay. This, however, exposed many ite was worked for feldspar and was used by local ceramic pegmatite pockets that would otherwise probably have never kilns, including the makers of the famous Kiyomizu ware of been found. In the Meiji era (1868–1912) Japanese authori- Kyoto, starting in the sixteenth century (Takebayashi 2004).

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ing for taking the specimen photographs, and to William Besse for preparing the map. JR also thanks Osamu Tamada and Kaz and Yukari Ito for organizing a trip to the Tanakami Mineral Museum. REFERENCES Ashkenazi, M. 2008. Handbook of Japanese mythology. New York: Oxford University Press. Hashimoto, K., Y. Hisada, T. Kutsukake, S. Nakano, H. Nishihashi, S. Nishimura, K. Sawada, K. Sugii, and G. Yoshida. 2000. Gra- nitic masses around Lake Biwa, southwest Japan: Part 5—The Tanakami Granite Pluton. Earth Science 54:380–92. [in Japanese with English abstract] Hayama, Y., and Y. Tainosho. 2000. Mesozoic to Cenozoic igneous activity and tectonism in the Ryoke Belt, southwestern Japan. The Island Arc 9:1–2. Ishihara, S., S. Nakano, and S. Terashima. 2005. Chemical charac- teristics of the Tanakami Granite, Kinki district—Particularly important role of the radioactive and REE components. Bulletin of the Geological Survey of Japan 56:93–98. Kasahara, K. 2002. A history of Japanese religion. Tokyo: Kosei Pub- lishing Company. Kinoshita, O. 1999. A migration model of magmatism explaining a ridge subduction, and its details on a statistical analysis of gran- ite ages in Cretaceous southwest Japan. The Island Arc 8:181–89. Kohno, T., S. Nakano, and U. Shimobayasi. 2009. Color mantle- zoning of alkali feldspar from small pegmatites in the Tanokami Granite Pluton, Shiga Prefecture, southwest Japan. Journal of the Geological Society of Japan 114:435–46. [in Japanese with English abstract] Kunz, G. F. 1920. Tsunashiro Wada [obituary]. American Mineralo- gist 6:109–13. London, D. 2008. Pegmatites. Special publication 10 of The Cana- dian Mineralogist. Mindat. 2008. Internet mineral and location database: http://www. mindat.org/. Morioka, K., Y. Tainosho, and H. Kagami. 2000. Rb-Sr isochron ages of the Cretaceous granitoids in the Ryoke Belt, Kinki dis- trict, southern Japan. The Island Arc 9:46–54. Nambu, M. 1970. Introduction to Japanese minerals. Ed. by editorial committee for the Introduction to Japanese Minerals organizing committee, International Mineralogical Association—Interna- tional Association on the Genesis of Ore Deposits Meeting 1970. Geological Survey of Japan. Obayoshi, T. 2000. Minerals of Tanakami region: Japan’s pegmatite Figure 20 (top). Milarite crystals to 1 mm long on microcline. producing areas #1. Nakatsugawa Mineral Museum. [in Japanese] Masutomi Museum (Kyoto) specimen. John Rakovan photomi- Rakovan, J. 2005a. News from Japan: Part 2—The Wada mineral crograph. collection, Ikuno mine, rainbow garnet, and mineral dealers in Japan. Rocks & Minerals 80:350–55. Figure 21 (above). A. E. Foote label on back of the microcline, ———. 2005b. News from Japan: Part 3—Ko mineral collection, schorl, quartz, and milarite specimen pictured in figures 19 Osaka and Tokyo shows, and collecting sakura-ishi and rainbow and 20. garnets. Rocks & Minerals 80:440–45. ———. 2008. Word to the Wise: NYF-type pegmatite. Rocks & As for mineral collecting today, local club excursions to Minerals 83:351–53. Sawada, Y., H. Kagami, I. Matsumoto, K. Ugii, S. Nakano, and Col- the site of the 1974 pocket are still held, although it has laborative Research Group for the Granites around Lake Biwa. been completely worked out. Most specimens being found 1994. A Cretaceous granitic ring complex and the Koto Cauldron are slightly waterworn crystals that collectors screen from around the southern part of Lake Biwa. Journal of the Geological sand and gravel from creek bottoms. A collecting trip to Society of Japan 100:217–33. [in Japanese with English abstract] Taira, T. 2001. Tectonic evolution of the Japanese Island Arc Sys- Tanakamiyama in 2005 (Rakovan 2005b) produced some tem. Annual Reviews in Earth and Planetary Science 29:109–34. interesting quartz and feldspar crystals in alluvial float, sug- Takebayashi, S. 2004. Fudo-kogaku (climate engineering). In Toshi- gesting that new discoveries may still be possible at this clas- kankyo-kogaku III. Tokyo: Sankai-do. sic locality. It is also recommended that Tanakami specimens Wada, M. 1994. Otsu-shinai no Yama-no-kami ni kansuru Oboega- ki (Notes on Mountain-god in Otsu City), Otsu-shi Rekishi- be further scrutinized because mineral species previously hakubutsukan Kenkyukiyo. Vol. 2. Otsu: Historical Museum. not described from the location may still be identified, as in Wada, T. 1904. Minerals of Japan. Translated by T. Ogawa. Tokyo. the case of milarite, described above. Yanagida, K. 1975. Senzo no Manashi. Tokyo: Chikuma-sosho. Yuhara, M., H. Kagami, and K. Nagao. 2000. Geochronological ACKNOWLEDGMENTS characterization and petrogenesis of granitoids in the Ryoke Belt, We are grateful to Kazuhiro Suzuki, Alfredo Petrov, and Daniel southwest Japan Arc: Constraints from K-Ar, Rb-Sr and Sm-Nd Dunkley for their helpful reviews of this manuscript, to Terry Huiz- systematics. Island Arc 9:64–80. q

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