Namibite and Hechtsbergite from the Nagatare Mine, Fukuoka Prefecture, Japan

Journal ofNamibite Mineralogical and hechtsbergite and Petrological from Nagatare, Sciences, Fukuoka Volume Prefecture,108, page 105Japan─ 110, 2013 105

LETTER

Namibite and hechtsbergite from the Nagatare mine, Fukuoka Prefecture, Japan

Seiichiro Uehara and Yohei Shirose

Department of Earth and Planetary Sciences, Faculty of Science, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan

Namibite [Cu(BiO)2VO4(OH)] and hechtsbergite [Bi2O(VO4)(OH)] were found with clinobisvanite, waylandite, eulytite, beyerite and bismutite at the Nagatare mine, Fukuoka Prefecture, Japan. This assemblage occurs as secondary minerals and forms crusts and euhedral crystals associated with lepidolite, quartz, albite and cookeite. Namibite forms a dark green powder with pearly luster. Hechtsbergite is yellow, and is found as fine isolated crystals or aggregates. The compositions of namibite and hechtsbergite, determined by electron microprobe, are

Cu0.98Bi1.92Al0.04O2 (V0.96Si0.07P0.02)O4 (OH) and Bi1.94Al0.01O(V1.00Si0.04)O4 (OH), respectively. The unit-cell parameters are a = 6.216(4), b = 7.384(6), c = 7.467(6) Å, α = 90.19(8), β = 108.65(7), γ = 107.36(8)°, V = 308.1(3) Å3 for namibite, and a = 6.954(5), b = 7.539(8), c = 10.870(9) Å, β = 106.87(5)°, V = 545.4(6) Å3 for hechtsbergite.

Keywords: Namibite, Hechtsbergite, Clinobisvanite, Waylandite, Nagatare Li-pegmatite

INTRODUCTION tare was previously recognized (Matsubara and Miyawa- ki, 2006), but it was not characterized in detail. The first mineralogical report of the Nagatare pegmatite Namibite, hechtsbergite, clinobisvanite, waylandite, was made by Ko (1933). The following year the pegma- eulytite, beyerite, and bismutite were found in the mineral tite was designated a national monument and named the collection of one of the authors (S.U.) and were collected ʻNagatare Pegmatite Dyke with Lepidoliteʼ. A part of the mainly in the late 1960s and 1970s; in the Yohachiro Oka- pegmatite is lithium-rich and was mined for lithium ore moto Mineral Collection housed at Kyushu University, during World War II. Excavated lithium ore, mainly com- Hakozaki, Fukuoka (Okamoto, 1944); and in specimens posed of lepidolite and elbaite was stockpiled after min- obtained in our field survey of the pegmatite since 2008. ing, although there is at present only a very small amount Namibite is a rare dark-green Cu-Bi-V-species, of remaining lithium ores. Mineralogical studies of the originally described from Khorixas, Namibia and was as- pegmatite were made by Shibata (1934) and Okamoto sumed to be an oxide mineral with the formula CuBi2VO6 (1944). After these investigations, several descriptive (von Knorring and Sahama, 1981). Mrázek et al. (1994) mineralogical studies were made before 1970 (e.g., Ito et redefined namibite as a vanadate with the formula 2+ 5+ al., 1955; Nagashima and Nagashima, 1960; Kuwano and Cu (BiO)2V O4(OH), based on a new wet chemical Hikita, 1967), although modern systematic and detailed analysis, IR spectroscopic and thermoanalytical data. Na- investigations of characteristic minerals in the Nagatare mibite has been described from 12 localities worldwide Li-pegmatite are missing. Therefore we have been rein- (Dunning and Cooper, 1998). The crystal structure of na- - vestigating lepidolite (Kataoka and Uehara, 2000), tour- mibite, was determined from single crystal X ray_ diffrac- maline (Shirose and Uehara, 2012), and other rare miner- tion data to be triclinic symmetry, space group P1, with a als from the deposit. In the present study so called = 6.210(1), b = 7.398(1), c = 7.471(1) Å, α = 90.10(1), β ʻbismuth ocherʼ was examined. It was identified to be bis- = 108.73(1), γ = 107.47(1)°, V = 308.22(8) Å3, Z = 2 mutite (Tsuji et al., 1977) and torbernite (Okamoto, 1944). (Kolitsch and Giester, 2000). Raman spectra of namibite The occurrence of clinobisvanite in the other from Naga- and other bismuth vanadates (dreyerite, pucherite and clinobisvanite) were recently reported (Frost et al., 2006) doi:10.2465/jmps.121022d Hechtsbergite - the V analog of atelestite - is a rare S. Uehara, [email protected] Corresponding author mineral with the formula Bi2O(VO4)(OH). It was origi- 106 S. Uehara and Y. Shirose nally described from the Hechtsberg quarry at Hausach, containing lepidolite, elbaite and petalite. The Cretaceous in Black Forest, Germany (Krause et al., 1997), where it Sawara granite and the Itoshima granodiorite are found in is associated with chrysocolla, bismutite, beyerite, namib- the Nagatare area. Many pegmatite dikes of 1 m to 200 m ite, mixite, and eulytite in minute cavities in gneiss. After in width cross-cut the Itoshima granodiorite (Karakida et the original description, hechtsbergite has been described al., 1994). The Nagatare lithium pegmatite contains minor from three other localities, Brejaúba, Minas Gerais, Brazil amounts of ʻbismuth ocherʼ in lepidolite-albite-quartz (Burns et al., 2000), the Clara Mine, Black Forest, Ger- pegmatite. Minerals in the ocher were identified as na- many (Kolitsch et al., 2004), and Smrkovec, western Bo- mibite, hechtsbergite, clinobisvanite, waylandite, eulytite, hemia, Czech Republic (Sejkora et al., 2004). The Naga- beyerite and bismutite by X-ray powder diffraction, scan- tare hechtsbergite is the 5th recognized occurrence in the ning electron microscopy (SEM) coupled with Energy world. Disperse Spectroscopy (EDS), and electron-microprobe This is the first discovery of namibite and hechtsber- analyses. gite in Japan. The present paper describes the X-ray dif- Dark green namibite occurs in the crusts is of 0.1 fraction and chemical data along with the mode of occur- mm in thickness together with yellow clinobisvanite rence of these rare minerals. (Figs. 1a and 1b). SEM observation indicates that the crusts of Bi-minerals are mainly found along grain OCCURRENCE AND PARAGENESIS boundaries and on cleavage faces of lepidolite. The crusts are composed of fine-grained namibite intergrown with The old Nagatare lithium mine is located at Nagatare, fine-grained clinobisvanite and waylandite (Fig. 2). Euhe- Fukuoka City, Fukuoka Prefecture, Japan (Lat. 34°35´N, dral, rhombohedral crystals of waylandite are also found Fig. 1(Uehara & Shirose) Long. 130°17´E). The ore body is aPrint granite width = 8 cmpegmatite in clinobisvanite and fine cookeite veins. On the two sam-

ples studied, these Bi-mineral aggregatesFig. are 2(Uehara mostly & Shirose) asso - Print width = 12 cm or 8cm

(a) (b) (a) (b)

1 cm

(d) 200 μm (c) 200 μm

Waylandite

Clinobisvanite Lepidolite

1 mm

Namibite

20 μm

(e) 100 μm

1 cm (e) C ookeite

1 mm Waylandite

Figure. 1. Secondary Bi-minerals form crusts composed of namib-

ite, clinobisvanite and waylandite (a), (b). Aggregates of euhedral 20 μm crystals of hechtsbergite (c), (d). Euhedral crystals of clinobis-

vanite (c), (e). (a) Lepidolite with colorful “bismuth ocher” com- Figure 2. Optical photomicrograph (a) and back-scattered electron

posed of namibite, clinobisvanite and waylandite. (b) Optical images (b), (c), (d), (e) for a crust of secondary Bi-minerals in

photomicrograph of the ʻocherʼin (a) green crystals are namibite. polished section (sample No. XN300). (a) Green namibite and (c) Quartz specimen with small pockets of yellow ʻocherʼ. (d) yellow clinobisvanite. (b) Back-scattered electron image of (a). Optical photomicrograph of (c), showing hechtsbergite. (e) Opti- (c) Enlarged view of the open rectangle shown in (b). (d) Namib- cal photomicrograph of (c), showing clinobisvanite. Images (a) ite crystal (brightest areas and compact aggregate of waylandite and (b) are from sample No. XN300, and (c), (d), and (e) are (medium intensity areas). (e) Enlarged view of the open rectan- from sample No.XN305. gle shown in (c). Namibite and hechtsbergite from Nagatare, Fukuoka Prefecture, Japan 107

each single crystal is 10 μm to 50 µm and are also found in cookeite (Figs. 3b and 3c). Eulytite is also found with cookeite in this specimen (Fig. 3d).

CHEMICAL COMPOSITION

Quantitative chemical analyses of namibite and hechtsbergite were carried out using a JEOL JXA8530F electron-probe microanalyser (EPMA), at an accelerating voltage of 15 kV, beam current of 20 nA, and beam diam- eters of 2 μm (sample No. XN300) and 5 µm (sample No. XN305). The standards used were fluorite (for FKα), co- rundum (for AlKα), quartz (for SiKα), apatite (for PKα

Figure 3. Photomicrograph (a) and back-scattered electron images and CaKα), Bi2Se3 (for BiMα), V2O5 (for VKα) and cu- (b), (c), (d) for hechtsbergite and eulytite in polished section prite (for CuKα). The ZAF method was used for data cor- (sample No. XN305). (a) Hechtsbergite under a stereomicro- rection. The water content was calculated according to - scope. (b) Back scattered electron image of (a). (c) Hechtsbergite stoichiometry. The averaged chemical composition of na- crystals in cookeite. Enlarged view of the open rectangle shown in (b). (d) Eulytite associated with cookeite. Color version of mibite, hechtsbergite and clinobisvanite from Nagatare Figure 3 is available online from http://japanlinkcenter.org/DN/ are presented in Table 1 together with comparative values JST.JSTAGE/jmps/121022d. from literature. The empirical formula of namibite, calculated on the basis of O = 6.5 per formula unit in the anhy- ciated with cookeite. The spherical namibite is made up drous part, is Cu0.98Bi1.92Al0.04O2 (V0.96Si0.07P0.02)O4 (OH), is of radiating aggregates of tabular or fibrous crystals of 10 in good agreement with previously published namibite μm to 20 μm in length (Fig. 2d) analyses (von Knorring and Sahama, 1981; Mrázek et al., Hechtsbergite is found in fine-grained yellow crusts 1994). The empirical formula of hechtsbergite, calculated or aggregates of euhedral crystals (Fig. 1c). The size of on the basis of O = 5.5 per formula unit in the anhydrous

Table 1. Chemical composition of namibite, hechtsbergite and clinobisvanite

* Number of analyzed points. ** The water content was calculated according to stoichiometry. 1. Namibite, Nagatare Mine, Fukuoka Prefec- ture, Japan (this study, sample No. XN300). 2. Namibite, Khorixas, Namibia (von Knorring and Sahama, 1981). 3. Namibite, Jáchymov,

Czech Republic (Mrázek et al., 1994). 4. Cu(BiO)2VO4OH. 5. Hechtsbergite, Nagatare Mine, Fukuoka prefecture, Japan (this study, sam-

ple No. XN305). 6. Hechtsbergite, Hechtsberg quarry, Germany (Krause et al., 1997). 7. Bi2O(OH)(VO4). 8. Clinobisvanite, Nagatare

Mine, Fukuoka Prefecture, Japan (this study). 9. BiVO4. 108 S. Uehara and Y. Shirose

- Table 2. X ray diffraction data for namibite part, is Bi1.94Al0.01O(V1.00Si0.04)O4 (OH), which is also in good agreement with the original hechtsbergite data (Krause et al., 1997). The Nagatare clinobisvanite has an end member composition.

CRYSTALLOGRAPHY

X-ray powder diffraction (XRD) data were collected on crystal fragments using a Rigaku RINT RAPIDII curved imaging plate microdiffractometer utilizing monochroma- tized CuKα radiation generated at 40 kV and 30 mA. The fragments were randomized using a Gandolfi-like motion about two axes (oscillation on ω and rotation on φ). The XRD data for namibite are listed in Table 2 together with those of the original description (von Knor- ring and Sahama, 1981). The original powder pattern of namibite had been indexed with a monoclinic unit cell. However, the crystal structure determination (Kolitsch and Giester, 2000) showed that the true symmetry is in fact triclinic. The unit-cell parameters from the original description were recalculated as shown in Table 3 with the namibite from the Iron Monarch deposit, South Aus- tralia (Kolitsch and Giester, 2000). The calculated unit- cell parameters for the present specimen are slightly smaller than those of the original material from Namibia, whereas these values agree well with those of the Iron Monarch namibite, which has an ideal composition within detection limits of energy-dispersive spectroscopic chemical analyses (Kolitsch and Giester, 2000). The XRD data for hechtsbergite is listed in Table 4 together with those of the original description (Krause et al., 1997). The calculated unit-cell parameters for the present specimen are a = 6.954(5), b = 7.539(8), c = 10.87(9) Å, β = 106.87(5) °, V = 545.4(6) Å3. These values are in good agreement with those of the type specimen, a = 6.971(1), b = 7.535(1), c = 10.881(1) Å, β = 107.00(1) °, V = 546.6 Å3.

Table 3. Unit-cell parameters for namibite

1. Nagatare, Fukuoka Prefecture, Japan (this study, sample No. XN300). Wl, waylandite. 2. Khorixas, Namibia (von Knorring and Sahama, 1981). 1. Nagatare, Fukuoka Prefecture, Japan (this study). 2. Khorixas, Namibia (von Knorring and Sahama, 1981)Recalculated with a triclinic unit cell. 3. Iron Monarch deposit, South Australia (Kolitsch and Giester, 2000). Namibite and hechtsbergite from Nagatare, Fukuoka Prefecture, Japan 109

Table 4. X-ray diffraction data for hechtsbergite

1. Nagatare, Fukuoka Prefecture, Japan (this study, Sample No. XN305). 2. Hechtsberg quarry, Germany (Krause et al., 1977).

DISCUSSION not been reported in previous studies (e.g., von Knorring and Sahama, 1981; Krause et al., 1997). Native bismuth The Nagatare Bi-minerals namibite, hechtsbergite, eulyt- in albite and quartz, bismuthinite in montebrasite, bismu- ite and waylandite, are closely associated with cookeite. totantalite and bismuthian microlite in lepidolite-quartz- This type of occurrence of namibite and hechtsbergite has albite-elbaite pegmatite were also identified in our study. 110 S. Uehara and Y. Shirose

The mineralogical properties of bismutotantalite from Na- Knorring, O. von and Sahama, T.G. (1981) Namibite, a new cop- gatare were described by Banno et al. (2001). All of these per-bismuth-vanadium mineral from Namibia. Schweizer- ische Mineralogische und Petrographische Mitteilungen, 61, bismuth minerals are scarcely found but they are charac- 7-12. teristic components of the later hydrothermal stage in this Ko, S. (1933) A pegmatite dyke, lepidolite and ceylonite from Na- highly evolved lithium pegmatite. gatare, Fukuoka Prefecture, Japan. Warerano Koubutu (Pre- sent ʻJournal of Geoscienceʼ), 2, 1-3 (in Japanese). ACKNOWLEDGMENTS Kolitsch, U. and Giester, G. (2000) The crystal structure of namibite, Cu(BiO)2VO4(OH), and revision of its symmetry. Ameri- can Mineralogist, 85, 1298-1301. We appreciate to Dr. Werner Krause (Huerth, Germany) Kolitsch, U., Blaß, U.G., Graf, H.-W. and Gröbner, J. (2004): and Professor John Rakovan of the Miami University for Neufunde aus der Grube Clara im mittleren Schwarzwald. critical reviewing of the manuscript. We are grateful also Lapis, 29, 18-23 (in German). to Dr. Atsushi Kyono, University of Tsukuba for editorial Krause, W., Bernhardt, H.-J., Blaß, G., Effenberger, H. and Graf, H.-W. (1997) Hechtsbergite, Bi O(OH)(VO ), a new mineral management. 2 4 from the Black Forest, Germany. Neues Jahrbuch für Miner- alogie Monatshefte, 271-287. SUPPLEMENTAL MATERIAL Kuwano, N. and Hikita, T. (1967) Montebrasite from Nagatare, Fukuoka, Japan. Chigaku Kenkyuu (Present ʻJournal of Color vevsion of Figure 3 is available online from http:// Geoscienceʼ), 18, 243-245 (in Japanese). Matsubara, S. and Miyawaki, R. (2006) Catalogue of Japanese japanlinkcenter.org/DN/JST.JSTAGE/jmps/121022d. Minerals. pp. 152, Tokai University Press, Hatano, Japan. Mrázek, Z., Veselovský, F., Moravcováušek, J., Moravcová, H. REFERENCES and Ondruš, P. (1994) Redefinition of namibite,

Cu(BiO)2VO4OH. Neues Jahrbuch für Mineralogie Monat- Banno, Y., Bunno, M., Haruna, M. and Oba, M. (2001) Stibiotan- shefte, 481-488. talite-group minerals in a lithium pegmatite from Nagatare, Nagashima, O. and Nagashima, K. (1960) The Rare Element Min- Fukuoka Prefecture, Japan. Journal of Mineralogical and Pet- erals of Japan. pp. 436, Present ʻMasutomi Museum of rological Sciences, 96, 205-209. Geoscienceʼ, Kyoto, Japan (in Japanese). Burns, P.C., Roberts, A.C., Stirling, J.A.R., Criddle, A.J. and Fein- Okamoto, Y. (1944) Minerals of Fukuoka Prefecture. pp. 208, Pre- 3+ 6+ glos, M.N. (2000) Dukeite, Bi24Cr8 O57(OH)6(H2O)3, a new sent Masutomi Museum of Geoscienceʼ, Kyoto, Japan (in mineral from Brejaúba, Minas Gerais, Brazil: Description Japanese). and crystal structure. American Mineralogist, 85, 1822-1827. Sejkora, J., Cejka, J., Hlousek, J., Novák, M. and Srein, V. (2004) Dunning, G.E. and Cooper, J.F.Jr. (1998) Namibite: a summary of Phosphowalpurgite, the (PO4)-dominant analogue of walpur- world occurrences. Mineralogical Record, 29, 163-166. gite, from Smrkovec, Slavkovsk Les Mountains, Czech Re- Frost, R.L, Henry, D.A, Weier, M.L., Martens, W. (2006) Raman public. Canadian Mineralogist, 42, 963-972.

spectroscopy of three, polymorphs of BiVO4: clinobisvanite, Shibata, H. (1934) A lithium pegmatite from Nagatare, Imajyuku,

dreyerite and pucherite, with comparisons to (VO4)3-bearing Itoshima, Fukuoka Prefecture, Japan. Journal of the Geologi- minerals: namibite, pottsite and schumacherite. Journal of cal Society of Japan, 41, 582-603 (in Japanese). Raman Spectroscopy, 37, 722-732. Shirose, Y. and Uehara, S. (2012) Chemical compositions of Li- Ito, J., Minato, H. and Okamoto, Y. (1955) On amblygonite from tourmaline and mica from Nagatare, Fukuoka Prefecture, Ja- Nagatare-yama, Fukuoka Prefecture. Journal of Mineralogi- pan. The Abstracts 2012 Annual Meeting of Japan Associa- - cal Society of Japan (Koubutugaku Zasshi), 2, 263-267 (In tion of Mineralogical Siences, R1 08, 38 (in Japanese). Japanese with English abstract). Tsuji, T., Ogawa, T., Yano, S., Kimura, T., Kuwano, N. and Toku- Karakida, Y., Tomita, S., Shimoyama, S. and Chijiwa. K (1994) maru, S. (1977) Revised Minerals of Fukuoka Prefecture. Geology of Fukuoka district. With Geological Sheet Map at Chigaku Kenkyu (Present ʻJournals of Geoscienceʼ), 28, 1:50,000. Geological Survey of Japan, pp. 192 (in Japanese 121-148 (in Japanese). with English abstract 7p). Kataoka, Y. and Uehara, S. (2000) Lepidolite in a lithium pegma- Manuscript received October 22, 2012 tite from Nagatare, Fukuoka Prefecture, Japan. Abstract of Manuscript accepted February 14, 2013 the Annual Meeting of the Mineralogical Society of Japan, 101 (in Japanese). Manuscript handled by Atsushi Kyono