九州大学学術情報リポジトリ Kyushu University Institutional Repository

Johannsenite from Teragōchi, Prefecture,

Momoi, Hitoshi Faculty of Science, Kyushu University

https://doi.org/10.5109/1543612

出版情報：九州大學理學部紀要 : Series D, Geology. 15 (1), pp.65-72, 1964-06-25. 九州大学理学部 バージョン： 権利関係： Mem． Fac． Sci．， Kyushu Univ．， Ser． D， Geology， Vol． XV， No．1， pp．65－72，2text一毎s，5tables， plate 6． May 31，1964

Johannsenite from Terag6chi， okayama Prefecture， Japan

By Hitoshi MoMoI

Abstract

Anew occurence of johannsenite has b㏄n found in manganese ore deposits at Terag6chi， Okayama Prefecture， Japan． The mineral occurs as a chief component of the massive manganess ore． Aggregates of bluish johannsenite crystals look quite similar to those of skam hedenbergite． It has following chemical composition： SiO2 48．02，TiO2 tr．， Al2030．80， Fe2030．30， FeO 3．20， MnO 27．53， MgO O．48， CaO 19．10， Na200．25， K200．04， H20＋0．23， H20－0．00， total 99．95 wt．％． Silky green variety with following composition was also found： SiO248．18， Al2030．80， Fe2031．00， FeO 4．82，MnO 26．29， MgO O．47， CaO 18．79， Na200．20， K200．04， H20＋0．10，’H20－0．00， total 100．69 wt．％． Optical properties for the blue johannsenite：α＝1．707，β＝1．720， γ＝1．736，γ一α＝0．029，2V（十）72°． Sp． gr．（blue variety）＝3．54（21°C）二 Unit cell dimensions ol）tained by X－ray powder method are：（blue variety）ao＝9．916A， bo＝9．107

む む む くコ む A，co＝5．280 A，β＝74°49’：（green variety）ao＝9．913 A， bo＝9．104 A， co＝5．274 A，βニ 74°49． Powder data and infrared spectra are also presented together with the heat－ ing effect of johannsenite．

Introduction

Occurrences of johannsenite have been recorded from Italy， Mexico， Aus－ tralia （Broken Hill）， New Jersey （Franklin Furnace）， New Mexico， and Oregon． Professor YosHIMuRA adviced me to study a specimen looking like hedenbergite Iabelled as from‘‘the Onagusa mine， Okayama Prefecture”in the KO collection of Kyushu University（YosHIMuRA，1952， P．103）． In 1959， Ivisited a manganese mine a七Terag6chi，1km． northwest of七he Nagusa copper mine， Katsuyama town， Country， Okayama Prefecture芥， and found there a mineral looking similar to七he specimen of the KO collection， in some piles of manganese ores． At that time， the deposits had not been working． The locality is shown in Figure 1． The specimell was identi6ed as johannsenite by chemical analyses， X－ray powder method， optical properties， and infrared absorption． This paper is a mineralogical description of the johannsenite， found for the 6rst time in Japan． The manganese ore deposits are developed in siliceous limestone and in green phyllite belonging七〇the Permian limestone beds and the Sangun meta－ morphic rocks（YAMADA，1941：MITSUNO，1963）． It was unable for me to observe the mode of occurrence of johannsenite in situ because of the aban－ doned mine． Only one massive outcrop， bearing johannsenite was recognized，

Manuscript received October 31，1963． ＊岡山県真庭郡勝山町寺河内 66 H．MOMOI

0κ冷γ質〃凶PRεF江πノRE

ONIANA 苓ノ×

TERAGOCHI

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Fig．1． Location of the manganese ore deposits bearing johannsenite（×）at Teragδchi， Okayama Pre－ f㏄ture， Japan． being heavily colltaminated with manganese dioxide． This ore body has a strike of N60°W， and a dip of NE 70°， which are near the general trend of the wall rocks， and is composed of johannsenite， manganese oxides， rhodonite， quartz， calcite， galena， and sphalerite． The main portion of johannsenite is seen fully al七ered to manganese dioxide， （todorokite with low crystallinity） and to powdery opaline silica． The oxide ore has fibrous radial texture pseudomorphous after johanllsenite． Tiny rhodonite crystal are seen around a quartz vein which traverses the johannsenite aggregate． Simultaneous crystallization of calcite and sulphides are observed among rhodonite crystals． Quartz veins are also seen accom－ panied by a small amount of galena and sphalerite． Bustamite and wollasto－ nite were not found in the johannsenite deposits．

Physical properties

Large johannsenite crystals are up to 15 cm． in length， and 5 mm． in width， and show long columner or 6brous texture． Radial or parallel growth Johannsenite from Teragδchi， Okayama Prefecture， Japan 67 is common． Color is light cobalt blue， bluish green or dark green with resinous to silky luster． Bluish crystal， surrounded zonally by greenish one， apPears very similar to that of hedenbergite． Specific gravity and optical properties were measured on a bluish crystal． Specific gravity；is 3．54 at 21°C（pycno－ meter method）． Optical proper七ies：α＝1．707，β＝1．720，γ＝1．736，γ一α＝0．029， 2V（十）72°， b＝Y， twinning plane（100）， C〈Z＝55°．

Chemical composition

Chemical analyses of blue and green johannsenites were made on pure ma七erials prepared by hand picking． The fiame photometric method was adopted for alkalies， and the common gravimetric mehtod for the other metal oxides． The results are given in Table 1， together with some other previous data． Atomic ratios were calculated on the basis of six oxygens wi七h the fol－ Iowing results； BI％e勉αγ‘e吻（Nao．02Mgo．03Cao．85）o．go（Mno，g6Fe”o．11Fe’”o．01Alo．02）1．10（Alo．02Si1．g8）2．ooO6．oo Gγθθ％勿αがθ垣（Nao．02Mgo．03Cao．83）o．88（Mno．91Fe”o．17Fe’”o．03Alo．02）1．13（Alo．02Si1．98）2．ooO6．oo 80th results are very close to the ideal formula of johannsenite， CaMnSi206． Differellce of color be七ween the two varieties lnay probably be due to their irOn COntentS．

Table 1． Chemical compositions of johannsenites

Broken Hill Mt． Civillina Teragδchi＊ Australia Italy Japan HUTTON SCHIAVINATO 1956 1953

Color Pale green Light blue Silky green

Sio2 48．39 47．90 48．02 48．18 Tio2 nn． tr． tr．

Al203 0．58 tr． 0．80 0．80 Fe203 nil？ 0．25 0．30 1．00 FeO 13．44 0．98 3．20 4．82 MnO 14．14 26．81 57．53 26．29 MgO 2．19 0．96 0．48 0．47 CaO 20．79 21．62 19．10 18．79 Na20 0．05 0．25 0．20 K20 0．09 0．04 0．04 H20＋ 0．08 0．26 0．23 0．10 H20－ 0．12 0．50 0．00 0．00 CO2 1．11

Total 99．87 100．39 99．95 100．69

＊Analyst： H． MoMoI 68 H．MOMOI

X’ray powder study

X－ray powder patterns were obtained by a Shimadzu X－ray diffractometer with五ltered Fe Kαradiation． The experimental conditions were：30 KV， 10mA， full scale 500 counts per second，七ime constant 2．50r 5．O seconds， scan－ ning speed 20r 4 degrees per minute， slits 3－2－0．4 mm． The readings of diffraction angles were corrected with an internal s七andard of silicon． The unit cell dimensions were determined from the following reflections：（600）， （060），（350），（531），and（750）． The indexing was made in referring to those of clinopyroxene by KuNo and HEss（1953）and by YAMAGucHI（1961）． The results are lis七ed in Tables 2 and 3． The observed and calculated d－values are in good agreement． The unit cell dimensions of七he Thrag6chi johannsenites

Table 2． X－ray powder data for johannsenite（blue）from Teragδchi， Okayama Prefecture， Japan （Fe Kα五1tered with Mn，λ＝1．9373 A） む

1 2θ dob8．（A） む dcalc．（A） む h一1202233120433133440241354104525603660453 男題。2器霞㌶泌認翌6。299額蟹四69肪器竺駆誕竺6H 1 00 0 B1⊥9一9錫3 10 0 々bOV4 8 ワ・ ｛ 045848650一 1 1232 1 111 1 1 11 π 411945195042186210 49530601560817246212262527229． 640040754 520748506443332222222222222221111111111111111111ロ 575200965533221111000983876666655555554498593030649434964173399718945319985411535238190736178287068411620978258401177510 33444445555555556666677777 7834478123345678124591234 5b3440撒ユ46撒釜22え撒日2メ6量βεβ三64433222222222222221111111111 111 11 ・ ． ・・・・・・… 2939055470808687979171207 ガ ロ ロ の ロ コ び コ ヴ ロ コ び コ コ コ ロ ロ コ コ コ ロ の コ ロ の ヴ ロ ロ 097518600224828533041 7045300 20 20 21

10 11 31．210200 1112一123031212041一〇202323110．2150424031233000235021026042．3152

｛

W W

● …

W WB W ◆ ． ・ ・ ● ・ ・ … ｛

B 一6512一126 1⊥ ｛ 77 8102275 2β一’72 79

83 85 ．

B： 1）road， w：weak． Johannsenite from Teragδchi， Okayama Prefecture， Japan 69

Tal）le 3、 Unit cell dimensions of johannsenites β L㏄ality Reference a。（A） b。（A） c。（A）

Teragδchi This paper 9．916 9．107 5．280 74°49’ Japan （Blue） Ditto． （Green） 9．913 9．104 5．279 74°49 Civillina SCHIAVINATO 9．81 9．02 5．26 75° Italy 1953 Herault KUNO and California HEss 9．854 9．024 5．263 75°40’ （Hedenbergite） 1953 are somewhat larger than those of an Italian specimen（ScHIAvINATo，1953）． The calculated densi七ies are 3．56g （blue） and 3．57g （green）．

In丘ared abso巧ption spectra

The infrared absorpiton spectra of blue johallnsenite were obtained with aHitachi double beam infrared spectrometer using KBr disks． The results are shown in Table 4 and Figure 2． The absorptions by CO2 and H20 are excluded because they were probably contaminated in air． The spectra of hedenbergite（FeO 18．75 wt．％）from the Mitate mine， are also shown in the same table and figure for comparison，s sake． It is clear that both minerals have very close resemblances in absorption． The absorp－ tions of johannseni七e are observed a七七he slightly Ionger sides in wave length than those of hedenbergite owillg to the absorp七ion difEerences between ferrous iron in hedenbergite and divalellt manganese in johannsenite．

Table 4． Infrared absorption spectra of johannsenite， its heating product， and related minerals

Hedenbergite Johannsenite ］ヨ【eated johann8enite Bustamite

Mitate mine Teragochi Kanoiri mine 1060 S 1062 S一SmS1080 S 1085 1020 1025 SSSS一W 一 S 955 S 952 945 s 940 905 W 910 905 S 905 855 S 860 660 VW 675 VW 685 （Wave加mber， cn1－1）

Heating Product of johannsen、ite

Johannsenite has a modi丘cation belonging to a high temperature form， called bustamite． This is a well known faCt since johannsenite was named （ScHALLER，1938）． The johannsenite from Terag6chi， described here， was also 70 H．MOMOI

WAVE LENGTH 9．o lo．o

ロOO “OO IOOO 900 800 ●8 WAVE NUM8ER ㎝ Fig．2． Infrared absorption spectra A： Hedenbergite from the Mitate mine， Miyazaki Pyefecture． B： Johannsenite from Teragδchi， Okayama Pref㏄ture． C： Heated johannsenite， ditto． D： Bustamite from the Kanoiri mine， ． easily modified into bustamite by heating a七1000°C for l hour in air． The heating Product with pale grey color was examined by the X－ray powder method and by the infrared absorption spectra in七he same condition to above． The results for the blue specimen are shown in Tables 4 and 5， and in Fligure 2． The infrared absorption spec七ra of the heated johannsenite were compared with those of bustamite from the Kanoiri mine， Tochigi Prefecture． They agree closely with each other． The X－ray powder data for the heated materials from Japan and from Australia（HuTToN，1956）are in good agreement in spite of the difference in iron content （FeO 320 in Japanese and 13．44 wt．％ in Australian）． The contents of calcium in the original johannsenite were， CaO 19．10 in Japanese and 20．79 wt．％in Australian． The structure of the heated products may be Johannsenite from Teragδchi， Okayan｝a Prefecture， Japan 71

Table 5． X－ray powder data of heated johannsenite

Johannsenite， heated in Ferroan johannsenite， heated in air，1070°C， air，1000°C，1hr． 15．5hrs． Broken］Hill， Terag㏄hi， Japan Australia

1 d（A） 1 d（A） PO 5 5 8 7．52 5。 1121172一32351101381一4333311一4347544443 3333222222 2222211 111 コ コ タ お ロ ロ コ コ コ コ コ コ コ ロ の コ ロ 549218587619602396 ⑳ 89霞。5竺釜肪。4塁巧豊5。石釦％U晶％一謬68

1 bb 、O b 23 333332 2222222222 111111コ 564239 1356072444 749927566074 6457379382 638308 835125249一〇〇689982092312一85 且 3 20一〇コ㊤95549432ユ一〇〇βココ6

－寸⊥ （b551⊥OV10

10

controled more effectively by七he calcium atoms．

Acknowledgm使t

Iexpress my sincere七hanks to Professor Toyofumi YosHIMuRA of Kyushu University for his guidance during七his work and also for his reading the manuscrip七． Thanks are due to Dr． Haruo SHIRozu for his reading the manu－ script and much advice， to Dr． Mayumi YosHINAGA for his discussion and advice， and also to Dr． Kichinosuke HENMI and Dr． Chiharu MITsuNo of Oka－ yama University， to Mr． Ichiro ToMIoKA， the mine－owller at Teragochi for their kind guides and advices in the 6eld work． Fur七her， this work was partly indebted to the Grant in Aid for Scientific Researches from the Department ＜）fEducation of Japan． 72 H．MOMOI

Re允rences

ALLEN， V． T． and FAHEY， J． J．（1953）： Johannsenite and ferroan johannsenite at Vanadium， New Mexico． ．4仇．刀弼πθγ．，38，883－890． HuTToN， C． O．（1956）： Manganpyrosmalite， bustamite， and ferroan johannsenite from Broken Hill， New South Wales， Australia． A仇．1協％θ㌍．，41，581－591． KuNo， Hisashi and HEss，正1． H．（1953）： Unit cell dimensions of clinoenstatite and pigionite in relation to the common pyroxenes．∠4糀． Jb耽． Soτ．，251，741－752． MITsuNo， Chiharu（1963）： Zur Kenntnis des Oberpal50zoikums in Ostlichen Chugoku， SUdwest・ Japan． GθoZ．」¢θp‡．1五γ08んτ？ηα σγ励勿．，γ20．12，419－443． ScHALLER， W． T．（1938）：Johannsenite， a new manganese pyroxene． A仇．1協％θγ．，23，575－ 582． ScHIAvlNATo， G．（1953）： Johannsenite of the deposit of manganese containing silicates at Mount Civillina， near Recoaro（Vicenza， Italy）． 丑θη（1．80¢．勿仇θγ．撹α1．，9，210－218． YAMADA， Setsuo（1941）：Geologic map of Japan，‘‘Kuze，， sheet． Scale 1：75，000． Geol． Surv， Japan （1951）． YAMAGucHI， Masaru（1961）：Chrome－diopsides in the Horoman and Higashi－Akaishi Perido－ tites， Japan． 1晩γ7τ． Fαo． S碗．，1ζyμ8んτL σ？zぜ勿．， Sθγ．1）， Gθol．，10，（2），233－245． YosHIMuRA， Toyofumi（1952）： 娩％9αηθ8θdθpos偽げみPαπ． Manganese Investigation As－ s㏄iation． 567 PP（in Japanese）． Hitoshi MOMOI

Johannsenite from Terag6chi， Okayama Prefecture

Plate 6 Explanation of Plate 6

Fig．1－2． Polished hand specimens of johannsenites from Teragδchi， Okayama Pre－ f㏄ture． 1 ● Spherulitic green johannsenite（J）cutted by quartz vein（Q）with silicified aureoles and by sphalerite vein （S）． 2． Fibrous green johannsenite（J）being partially replaced by pink rhodonite （R）． Lower part（Q）consists of rhodonite（grey）， sphalerite（dark spots）， and quartz（white）． Fig．3－4． Microphotographs of Johannsenite－rhodonite ore． Crossed nicoles． 3． Relicts of johannsenites（J）replaced by rhodonite （R）and carbonitization along the columner texture of johannsenite． 4 Idiomorphic rhodonites（R）and calcites（C）replaced johannsenite（J）．

Photos by H． MoMOI Mem． Fac． Sci．， Kyushu Univ．， Ser． D， Geology， Vol． XV Plate 6

1 2

シぷ ーe麟欝難ー

套盤癖癖難曝欝 0 1cm

0 1mm

H．MoMoI：Johannsenite from Terag6chi， Okayama Prefecture