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NEW OCCURRENCES of TODOROKITE* C. Fnonlnr 1960 THE AMERICAN MINERALOGIST, VOL. 45, NOVEMBER_DECEMBER' NEW OCCURRENCES OF TODOROKITE* C. FnoNlnr-, U. B. M.q.nvrn exl J. ho, Harvard' Lrni'ters'ity, Combridge, M assachus etts. Asstnact Na' K)z Chemical, *-ray and other data are given for todorokite, (Mn, Mg, Ca, Ba' Hiittenberg' MnsOrz'3HzO, from Charco Redondo, Cuba, Farragudo, Portugal, and Brazil' and Austria. Additional localities at Roman6che, France, Saipan Island, Bahia, Straczek (1958) is identical Sterling Hiil, New Jersey, are noted. Delatorreite of Simon and with todorokite. INrnooucrroN We have identified todorokite, a manganeseoxide mineral hitherto ore from the known only from Japan (Yoshimura, 1934),in manganese Charco Redondo district, Cuba, and in Museum specimensfrom six additional localities.Delatorreite, briefly mentioned as a new mineral in a publication by simon and Straczek(1958) on the charco Redondo deposit that appearedduring the courseof our work, is identical with todorokite. Our determinationof this material as todorokite is basedon a type specimenobtained by W' F. Foshagin 1946in Japan and now depositedin the U. S. National Museum. Todorokite apparently is a widespreadmineral and in the charco Redondodeposit at leasthas been an important ore. Locerrrrr's Charco Red.onjo,Cubo. The material from Charco Redondo is described in detail in an accompanying paper by Straczek, Iloren, Ross and War- shaw (1960). Our specimenswere obtained by T' C' Marvin in 1955 during a survey made for the Union Carbide Ore Company' In general they have a slightly divergent or exfoliate fine-columnar to fibrous struc- ture (Fig. 1). The fibersrange up to about 10 cm' in Iength' Fracture sur- faces tend to be somewhat curved and show a weak silky sheen.The luster on surfacesbroken acrossthe fibrosity is dull. The color of the mineral is dark brownish black. The specific gravity as measured on small grains on the Berman balancevaried between3.1 and 3.4 and un- doubtediy is low becauseof the fibrousstructure. The hardnessis low but could not be measuredaccurately. A chemicalanalysis of the mineral is cited in Table 1, and the r-ray powder clata are given in Table 2 and Fig. 2. Firragud.o,Portugal. A stalactitic massof todorokite (Fig' 1) was found in a small collection of secondary manganeseminerals, chiefly crypto- x Contribution from the Department of Mineralogy, Harvard University, No. 339. r167 1168 C. FRONDDL, U. B. MARVIN AND T. ITO Frc. (right) and from Farragudo, Portugal (left). About f natural size. melane,from this locality. The material is soft and porous, and shows the slightly divergent, long fibrous mode of aggregation and dark brown to brownishblack color that appearsto be typical of todorokite. A crude concentriclayering is presentand someof the inner layers have a dense Hutienberg Jopon tlrll,.l .eoo,h_!_!rrrrrr ru tQ J() 40 50 60 70 80 90 Frc, 2. Powder pattern diagrams. NEW OCCURRENCDS OF TOI)OROKITE tt69 T.qsrn 1. Cnnurc,q.r-ANn'r-vsns on Tooonontp Charco TaPan Farragudo Fliittenberg Redondo tyoshimura, 1934) MnOz 70.2s 69.57 7t.7s 65.59 MnO tr.19 11.65 8.62 t2.37 CaO 0.96 2.30 |.40 328 SrO* - 0.01 - 0.05 - 0.01 BaO 0.00x 0.19 4.32 2.05 LirO* - 0.05 - 0.001 - 0.01 NurO 1.16 t.t4 0.17 0.21 KsO 0.61 0.35 091 0.54 Meo 3 .90 3.25 2.r3 1.01 Niox - 0.001 - 0.05 - 0.001 CoOt - 0.01 - 0.05 CuO 0.001 0.01 0.001 Pbo* - 0.00x -001 0.00x Al:O: tr. tr. tr. 0.28 FezO: 0 .01 tr. 0.02 0.20 sio: 0.68 o.27 0.23 0.45 SO: 0.24 0.14 0.14 0.28 HzO 10.50 10.83 9.95 11.28 Rem. (Note 1) (Note 2) (Note 3) (Note 4) Total 99.73 1C0.16 99.E9 99.24 Moiecular Quotients MnO: 5.12 4.87 6.79 4.30 MnO 11 L 1 (Mg, Ca,Ba, Na, K)O 0.89 0.90 0 .98 0.61 HrO 3.69 3.66 4.5s 3.10 Note1. Rem.is PrOs0.13, MoOa 0.05, ZnO 0.00x, VzOs 0'C0x, TiOg 0 00x,Ag tr'' Astr' Note2. Rem.is MoOa0.05, Scror tr., (Y, Yb):Ottr', Ag'tr', R,O30'26' Note3. Rem.is MoOs0.03, ZnO 0.00x, ZrOztr , (Y, Yb)rO3tr', RzOa0'2' Note4. Rem.is PzOs042, TiOz tr., insol.1.28' + Determinationsby opticalspectrograph. structure and earthy luster. A chemicalanalysis is given in Table 1, and the x-ray powder data in Table2 and Fig. 2' Hiittenberg,carinthia, Austria. This material comprised nodular masses about 5 cm. in diameter, without matrix, with an indistinct fibrous structure and coarseconcentric layering. The material is very fragile and soft, falling to pieceswhen handled,and is so light and porousas to float on water. The color is brown, Iighter in tone than that from Charco Redondo. The luster of fracture surfacesis dull, as in the other occur- rencesof todorokite, but the smooth outer surfaceof the noduleshas a C. FRONDEL, U. B, MARVIN AND J. ITO Tl.er-r,2. X-Rev Poworn Dlre lon Tooonorrrr Filtered iron radiation, in Angstroms Farragudo, arco Redondo, Todoroki Mine, lliittenberg, Roman€che, Portugal. Cuba Japan Austria France 10 9.60 10 9.68 10 9.60 +d 7.r3 +d 7.rs 3 7.02 8 4.80 8 4.80 8 4.79 1d 4.45 -rrd 4.45 l 3.48 +d 3.40 1 3.20 i 32r 1 3.10 3 3.10 3 2.46 2 2.46 2 2.46 5 2.40 4 2.39 5 2.40 4 2.34 li 2.34 2 233 2 2.23 2 2.22 2 2.23 +d 2.rs i d 2.rs 2 2.15 2 1.98 2 1.98 | 2.00 + r.92 + 1.92 | 1.78 r 1.74 | 1.75 1 d r.73 21 1.69 l 1.53 I + r.s4 1 1.55 2 3 149 2 1.42 3 1.42 4 1.43 I | 1.39 1 1.39 + r.4a t d:difiuse line. faint bronzy appearance.A few thin intercalatedlayers of a brack dense mineral were identified by *-rays as pyrolusite. A chemical analysis of the mineral, cited in Table 1, showsit to be relatively high in Ba. The r-ray powder data are given in Table 2 and Fig. 2. Meixner (1957)notes that a soft "wad" occursat Hi.ittenbergtogether with hard, black coatingsof secondary manganeseminerals that probably include cryptomelane and hollandite. saipan, Mariana Islands, Pacif.c ocean. This material was identicar in form of aggregation and color with that from charco Redondo. rt is rera- tively brittle and hard, however, becauseit is intimatery admixed with finely divided silica. Although the mineral appears homogeneousto the eye, grains when leachedwith acid leave a skeletonof silica amounting NDW OCCURRENCESOF TODOROKITE ITTT in some instancesto 50 per cent of the sample or more. Efforts to remove the silica by treatment with heavy Iiquids were not successfuland a chemical analysis was not undertaken. A semi-quantitative spectro- graphic analysisrevealed that Mg was presentin amounts greater than ba und Ca. Small depositsof unidentified manganeseoxides have been mined on Saipan and their geologyhas been describedby Cloud, Schmidt and Burke (1956). RomanAche,Fronce. A Museum specimen from this locality showed a diffuse d.arkeningat about d 7't h. The summary description by Lacroix (1910) of romanechite from Romandchementioned soft to porous fibrous varieties that probably refer in part to todorokite. Sterling Hill,, New Jersey. Todorokite was identified in a small collection of secondary manganese oxides from the old surface workings at the south end of the orebody at this place (Palache,1935)' The todorokite forms soft, dark brownish black masses with a confused leafy-fibrous structure. It occurs associatedwith chalcophanite and secondary calcite crystals in altering franklinite-willemite ore. Efforts to separate the todorokite from admixed chalcophanite were unsuccessfuland a chemical analysis was not made. Bahia, Brazil. We have also identified todorokite by r-ray means as a rare constituent of the manganeseoxide depositsat Saudeand at Urandi, Bahia. The deposits of both areas are largely the result of supergeneen- richment of metamorphic country rock containing spessartiteand other manganeseminerals. Oprrcar- Pnopr'ntrBs Under the microscopethe mineral is dark brown in color and is not well (010) and mura (1934) the mineral from Japan is lath-like, flattened on elongated[6Ot] *it6 terminal edgesinclined ca. 60o and 70" to [001]' 1172 c. FRONDEL,U. B. MARVIN AND J. ITO cleavageson (100)and (010).He statesthat y: 6 with z nearor paraller hOf] ana absorption Z>X..Our sample of the Japanesematerial con_ formed to the description first given above, although it was reratively dark colored and had a tendency to break into neediesrather than into laths or plates. Tnenuer BBnavrt_rn decompositionproducts that presumablycontain the Ba, Mg, and Ca re_ ported in the chemical analyses. X-nav PowoBn Dera Crrpurcal Couposrtrox case with the complex manganeseoxides. The crystal chemistry of these minerals generally involves both the coupled substitution of ions of unlike valence in one or more cation positionsand valence-coupredomissions, and a satisfactoryanswer usually is not obtained until the crystal struc- ture is worked out. The ratios of the charco Redondoand Farragudoma- terial suggestthat the idealized formula contains a total of 7 caiions and 12 oxygenions, probably as (Mn2, Mg, Ca, Ba, K, Na)zMnarOrz.3HzO The amount of water presentdoes not appear to be lessthan 3IIzO and may be greater. The SiO2, FerOe,AlzOa, SO3, and pzOr reDorted in the NEW OCCURRENCES OF TODOROKITD ll73 analysesmay be due to admixture.
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