Minerals of the УагпtI"аsk Pegmatite.

Transcription

1 GEOL. FOREN. FORH.ANDL. Bd. 60. Н Minerals of the Уагпt"аsk Pegatite. X. XRay Studies оп Triphylite Varulite and their Oxidation Products" Ву CARL OLOF BJORLNG апа А. WESTGREN. ЩS. received "/ 938.) rl connection ith ап iпvеigаtiоп arted Ьу Р. QUENSEL оп iпегals reccnt]y discovered at Varutrask in north Seden опе о! thc present authors (WESTGREN) Ьав at the reque о! Professor QUENSEL taken sое Хгау poder photographs of triphylite ferrisicklerite and heterosite. ТЬс patterns thus obtained соуегеа the diffraction range 58 5О They ere гертоаисеа in the report in hich QUENSEL describes these suьапсеs proving that еась о! the тау Ье considered to Ье а special ineral.! The Хгау inveigation has no Ьееп carried оп to the point here it сап Ье shon that although the sресiепs тау Ье ooked ироп аа three different inerals they ате at the вате tie very siilar in ructure. This seeed already likely {тот ап inspection о! the poder photographs containing the lea deviated interferences hich reseыdd each other rikingly апа а closer ехаiпаtiоп of the coplete set of poder photographs has proved it Ьеуопа doubt. Triphylite Ьаа Ьееп inveigated Ьу В. GOSSNER апа Н. STRUNZ ho found that the nuber от atos in its translation group i8 the sае ав that in olivine and onticellite hile the diensions о! its unit сен agree closely ith those of the said iпегаls.2 They Ьауе therefore concluded that the atoic grouping о! triphylite is analogous to that о! olivine апа onticellite. ts urrit сеl dillensions ere deterined to Ье а = 4.67 Ь = 0.34 апа с = 6.00 А. ТЬе interferences of our tl'iphyite poder photographs ere {оиnа to Ье in good ассога ith these lattice diепsiоns. Ав ау Ье seen in ТаЫе the sin2 l/values agree perfectly ith those calculated оп the assuption that the identity periods аге а = 4.7 Ь = аnа с =6.038 А. ТЬе inera i8 thus orthorhobic ith ап axial ratio о! : : Р. QUENSEL Geol. Foren. l<'i\rhandl В. GOSSNER ald Н. STRtтNZ Zeitschr. f. Кriaogr

2 68 CARL ОСОЕ BJORLNG AND А. WESTGREN. [Jan.Febl n the report entioned QUENSEL ated that Н. VON ECKERMANN after having inveigated tinned cryal of lt as thougm to Ье triphylite concluded that its syetry тау Ье loer than orthorhobic. n order to te this e have taken to Laue photographs о! а inute sliver о! the ineral in еась case ith the priary Xray Ьеат parallel to опе о! the ain ахев. ТЬе diagras do not support the conclusion о! VON ECKERMANN but are inead in coplete accord ith the orthorhobic сен ated above. Moreover F. ZAMBONN and F. MALOSSl have easured artificially produced very e developed cryals о! lithiophilite LiMnP04' and found the to Ье orthorhobic ith ап axial ratio of : : i. е. very nearly the вате ав that о! triphylite. There triphylite. is tbus по reason to doubt the ortborhobic syllletry of Further the poder photographs of ferrisicklerite and heterosite provc that these inerals cryallize orthorlloc too. Their unit сен diensions Ьауе Ьееп deterined for ferrisicklerite to Ье а = Ь = с = 5.9(59 А and for heterosite to Ье а =4.760 Ь =9.680 с =5.89 А. n TabJes 2 and 3 тау Ье seen ho ell the sin2 6values о! the Xray patterns agree ith those calculated. Although the lattice diensions о! the three inerals do not differ very тись а decrease тау Ье noted fro tripbylite through ferrisicklerite to heterosite. ТЬе unit сен volue is for triphylite 295 for ferrisicklerite 287 and {ог heterosite 268 Аз. This successive shrinking of the lattice is evidently connected ith the leaching о! lithiu hich.according to QUENSEL accopanies the successive oxidation о! the iron and the anganese. ТЬе forulae о! the inerals тау Ье ritten for triphylite [Li (Мп Fe)] РО4' for ferrisicklerite [(Li.Mn) Fe] РО4 alld {ог heterosite [Мп Fe] РО4' Ав there are evidelltly four forula ullits presellt in the unit cel in еась о! the inerals the trallslatioll group о! triphylite consis о! 28 atos that о! heterosite of 24 atos alld tbat о! ferrisicklerite о! ап interediate nuber. As тау Ье аееп in ТаЫев 3 the relative illtensity о! the Хгау interferences is practically the аате for а three inerals. As already entioned they u consequently Ье siilarly built ир. Reflectiolls h О ith h + odd and О k ith k odd аге issing in ан the poder pbotographs indicating that the inerals аге ан isoorphous to D \ the арасе group о! oliville. Starting {гот the approxiate paraeter values о! oivine given Ьу W. L. BRAGG and G. В. BROWN2 it has Ьееп F. ZAMBONN and F. MALossr Zeitschr. {. Kriallogr W. L. ВЕАоа and а. В. BROWN Zeitschr. f. Kriallogr

3 Bd 60. Н..] l\пnеrаls OF ТНЕ VARUT.RASK PEGMATTE. 69 possible Ьу syeatic variation of the and coparison beteen calculated and observed intensities to find out а ructure that u Ье approxiately correct 'uiz. 4 Mn and Fe in 4 (с); 2nи =_ 0 ; 2nУ = 00 ; 4 Р ln 4 (с); 2nи2 = 50 ' 4 О! Ш 4 (с); 2nuз = 90 ; 2nу2= 35 ' 2nvз = 20 ; 4 ОП ln 4 (с); 2nи4 = 90 ' 2nУ4 = 60 ' 2nх 70 ; 2nу 60 ; 2nz = 0. 8 ОШ ln 8 (а); Ав тау Ье seen in ТаЫе 3 the agreeent beteen the calculated and observed intensities is not quite perfect but the discrepancies are во illsignificant that the ructure тау Ье taken ав aillly correct. That it canllot Ье very тись in error is аlво illdicated Ьу the fact that the paraeter уаlиев are alo the вате ав those of Ollticellite MgCaSi04 hich Ьауе been deterilled Ьу G. В. BROWN аllа J. WEST.l ТЬе Р04 lattice of heterosite is the вате ав the Si04 arrangeent of. Ollticellite апа the Мl апа Fe atos Ьауе the вате position in the forer ineral ав the Са atos in the latter. Ав the atoic groupillg ill triphylite is evidently Уегу siilar to that of heterosite their Р О аllа heavier etal atos nlu Ье arranged in the sае ay. ТЬе авsuption of GOSSNER апа STRUNZ that the Mn and Fe atos of triphylite are situated in а set of syetry centres has thus not been verified. Fro the сlове allalogy beteell triphylite and onticellite it ау Ье concluded tllat tlle Li atos ill the forer illeral are situated ill 4 (а) i. е. оп the points 000 OO НО B. n ferrisicklerite this position is only partially occupied Ьу Li atos and in heterosite ан its points are unoccupied. t is rather aonishing that the oxidation of the heavier etals аllа the loss of the lithiu is not accopanied Ьу а ore radical change in ructure than а ere eliination 0 the lithiu atos fro tlle lattice of triphylite. t u Ье гееьегеd that the difference in atoic size beteen tri and bivalent anganese (or iron) is quite considerable. ТЬе ructure found for heterosite is аlво range in vie of the fact reported Ьу У. CAGLOТ that FeP04 has the sae ructure ав а quartz.2 That ill this саве the atoic arrangeellt of triphyite is argely aintained тау Ье аие to the occurring of the cheical processes at such а lo teperature that any change in ructure is prevented. Heterosite ight thus Ье ап ullable product. То deterille if this ight Ье the саве e Ьауе leated the illera for а fe inutes at about G. В. ВЮWN and J. WEST Zeitschr. f. Kriallogr Z V. CAGLJOT Rend. Accad. Lincei (6)

4 70 CARL OLOF BJORLlNG AND А. 'VESTGREN. [Т an.febl ТаЫе. h k 02 0 } 20 2 } } } \ 3 f 42 Poder Photographs of Triphylite. sin'!! оьа. ;' calc. lоь { } { 0.43 } i i 0.97 l' i { 832 } : : { } { } v v v \\' : VW! ] '. h kl CrK Radiation. sin'! оьв. calc. ' } { ::; t i r i 0.<653 : ; { \ {g: } < obs. щ щ щ v v 5О0е С. When the poder thus treated as inveigated Ьу eans о! Xrays it as found that it had changed. The lines о! its Хтау patterns ere blurred and indiinct. When the ineral had Ьееп heattreated in the вате ay for about а day its poder photographs ere copletely changed. The lines of heterosite had disappeared and ere replaced Ьу а great ultitude of ne reflections shoing that the ineral had Ьееп transfored into а product ith а very coplicated ructure. The reflections ere far too питетоив to Ье explained Ьу ап atoic grouping of the aquartz type. We have also taken soe Хтау po"'der photographs of the inerals varulite and Mnalluaudite hich according to QUENSEL correspond to triphylite and ferrisicklerite but contain Na inead of Li. Their Хтау patterns have soehat diffuse lines but they sho diinctly that the inerals of the Naseries are not isoorphous to those contain

5 Bd 60. Н..] MNERALS OF ТНЕ VARUTRASK PEGMATTE. 7 ТаЫе 2. Poder Photographs of FerriSicklerite. СТК Radiation. h k l 02 0 \ 20 J } в'!! sin'! obs. h k! оьв. calc. obs. calc.! v { } v i v v i l' r l' 776 } i \ v \У v " Obs. \У v ing Li. Varulite and Mnalluaudite see hoever to Ье related to еась other in the вате ay as triphylite and ferrisicklerite. Their Xray patterns reseble еась other closely but the lines ое Mnalluaudite are soe hat displaced in thc direction of larger diffraction angles shoing that its lattice diensiolls are saller than those о! varulite. ТЬе oxidation ое the iron ое varulite is accopanied Ьу а corresponding leaching ое sodiu and this evidelltly brings about а shrillkage ое the lattice diensions ав in the саве ое the transforation ое tripllylite illto ferri sicklerite. Havillg theoretically deduced а ineral hich Ье called Napurpuritc QUENSEL ЬаБ llow obtailled speciens fro Varutrask that evidently collsi ое this suballce alld thus represellt the end product fored Ъу the coplete oxidatioll of varulite ог Mllaluaudite. Their Р. QUENSEL!ос. cit. р. 96.

6 72 CARL OLOF BJORLNG AND А. WESTGREN. [Jan.Febr hk \ 2 ( ! ТаЫе 3. Poder Photographs of Heterosite. ОЬ sin2 fi оаlо { } ОЬ8. оаl0. VW VW v v W g:; : ' О.;; { : 7 ' h kl } } 32 4 СтК Radiation. sin' Ī ОЬ8. оаlо. оьв. i 00. i ОА398 i i i i VW W { g: : } О.57Н VW VW 87 { : ;} 873 { з [ { Xray poder photographs reseble neither those о! varulite or Mnaluaudite nor those о! heterosite. They contain а very large питьет of lines proving that the ructure о! Napurpurite is exceedingly coplicated. When the anganese о! Mnalluaudite is oxidized its atoic grouping because of the largeness о! the reoved Naatos evidently сап la по longer but changes into а ne one. The inveigatjon of the varulite series о! inerals has so {ат only Ьееп о! an orientating character. t ill Ье carried оп ith а vie о! deterining the ructure о! varulite hich тау Ье possible through the analysis о! artificially produced NaFeP04 о! NaCuP04 cryals. А ore coplete deterination о! the triphyliteheterosite ructures ill also Ье attepted.