Charoite, a new mineral and a new jewelry stone

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<ul><li><p>This article was downloaded by: [University of North Carolina]On: 11 November 2014, At: 16:16Publisher: Taylor &amp; FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office:Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK</p><p>International Geology ReviewPublication details, including instructions for authors and subscriptioninformation:</p><p>Charoite, a new mineral and a new jewelrystoneV. P. RogovaPublished online: 29 Jun 2010.</p><p>To cite this article: V. P. Rogova (1979) Charoite, a new mineral and a new jewelry stone, InternationalGeology Review, 21:5, 615-620, DOI: 10.1080/00206818209467101</p><p>To link to this article:</p><p>PLEASE SCROLL DOWN FOR ARTICLE</p><p>Taylor &amp; Francis makes every effort to ensure the accuracy of all the information (theContent) contained in the publications on our platform. However, Taylor &amp; Francis, ouragents, and our licensors make no representations or warranties whatsoever as to theaccuracy, completeness, or suitability for any purpose of the Content. Any opinions and viewsexpressed in this publication are the opinions and views of the authors, and are not the viewsof or endorsed by Taylor &amp; Francis. The accuracy of the Content should not be relied uponand should be independently verified with primary sources of information. Taylor and Francisshall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses,damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly inconnection with, in relation to or arising out of the use of the Content.</p><p>This article may be used for research, teaching, and private study purposes. Any substantialor systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, ordistribution in any form to anyone is expressly forbidden. Terms &amp; Conditions of access anduse can be found at</p><p></p></li><li><p>Charoite, a new mineral and a new jewelry stone1 </p><p>V.P. Rogova ef al. </p><p>The mineral is named for the region of its occurrence - the middle course of the Chary River. The deposit of charoite is localized within the Murun syenite massif, occurring at the junction of the Aldan crystalline shield and the Siberian Platform. The southern part of the massif (Greater Murun) cuts Archean crys-talline schists and gneisses; the northeastern part ( Lesser Murun), Cambrian marly lime-stones and dolomites. Rocks of the Murun Massif belong to a Mesozoic magmatic complex. The Aldan Shield is also similar in petrochemi-cal features to rocks of the intrusive of the Central Aldan region (Bilibin, 1959). The formation of the massif occurred in three phases. The earliest formations are flows of trachyte and pseudoleucite trachyte, having limited distribution. The flows of effusives are cut by intrusive alkalic rocks, consisting of nepheline - and aegirine - syenites, forming the main part of the massif. The magmatic stage is concluded by the injection of a dike complex, in which there are present alkalic pegmatites, pseudoleucite tinguaites, solvs-bergites, and grorudites. Pseudoleucite effu-sive, intrusive, and vein rocks, both melano-cratic and leucocratic, are widely developed within the Lesser Murun (Rogova, 1966). </p><p>In the pseudoleucite rocks there are present in variable amounts K-feldspar, kalsilite, mel-anite, aegirine, apatite, and a ra re zirconium silicate, wadeite (Rogova and Sidorenko, 1964). </p><p>In the border parts of the massif, and also within the zone of tectonic disturbance, wide bands of K-feldspar metasomatites are de-veloped. In metasomatites enriched in K at the contact with limestone there were formed un-usual K-Ca minerals: charoite, canasite, and tinaksite (Rogov et a l . , 1965). The tempera-ture of homogenization of gas-liquid inclusions </p><p>Considered and recommended for publication by the Commission on New Minerals and Mineral Names, All Union Mineralogical Society, Oct. 27, 1976. Recommended by the Commission on New Minerals, IMA, June 22, 1977. </p><p>Translated by Michael Fleischer from Charoitnovyy mineral i novyy yuvelirno-podelochnyy kamen', Vses. Mineralog. Obshch. Zapiski, 1978, no. 1, p. 94-100. Co-authors with Rogova are Yu.G. Rogov, V.A. Drits, and N.N. Kuznetsova. </p><p>in tinaksite is 400 C. Charoite- and K-feldspar-containing metasomatites have been aegirinized. </p><p>Charoite is the principal rock-forming mineral in the metasomatites and constitutes 50-90% of the rock (fig. 1). It is sometimes developed along the periphery of platy crystals of canasite or fills interstices between them. </p><p>The color of charoite is lilac of various shades to violet. Density 2. 54, hardness (PMT-3, load 50g, 12 measurements) 412 6 kg/mm2. Charoite forms finely fibrous aggregates with vitreous luster; in aggregates with parallel fibrous structure there is observed silky luster. The mineral is insoluble in acids. On crushing elongated fragments with rectangu-lar boundaries are formed. Cleavage is average in three directions. The angle between the planes of prismatic cleavage is 124; the angle between the planes of the prismatic and pina-coidal cleavages on (001 \ is 104. </p><p>The optical properties of charoite were studied in immersion preparations and in thin sections. The mineral is biaxial, positive, colorless in section. In thick fragments in immersion it is pleochroic: Z colorless, X rose-colored. The dispersion of the optic axes is variable. Indices of refraction were mea-sured in optically oriented sections: y = 1. 559 0. 002, 0 = 1 . 553 0. 002, a = 1. 550 0.002, y - a = 0.009, 2V = 28-30 (mea-sured on the Fedorov stage). Elongation posi-tive, X = b, Z c = 5 (fig. 2). The optical properties permit one to assume that the min-eral is monoclinic. In physical properties the mineral differs from canasite, similar in chem-ical composition ( Dorfman et a l . , 1959). </p><p>For chemical analysis (table 1) fine t rans-parent plates of the new mineral were selected under the binoculars. The homogeneity of charoite was confirmed by electron microscope study ( suspension method): aggregates of the mineral consist of homogeneous elongated particles of rectangular form (fig. 3). Spec-trograph^ analysis showed the following in the mineral: tenths of a percent of Pb, La, and Mn; thousandths of a percent of Zr and Y. Ba, Sr, and Mn are distributed uniformly in charoite (fig. 4). Analysis 3 (table 1) was calculated to the following formula: ( Cai. 57 Nao. 5lKo. 93Sro. 03Bao. 07) 3. 11 (Si40io) ((OH) 0. 58FQ. 28) 0. 78' 0- 72H20, Z = 18. </p><p>Internat. Geology Rev., v. 21, no. 5 IGR is not registered with the Copyright Clearance Center, Inc. </p><p>615 </p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Uni</p><p>vers</p><p>ity o</p><p>f N</p><p>orth</p><p> Car</p><p>olin</p><p>a] a</p><p>t 16:</p><p>16 1</p><p>1 N</p><p>ovem</p><p>ber </p><p>2014</p></li><li><p>INTERNATIONAL GEOLOGY REVIEW </p><p>FIGURE 1. Finely fibrous aggregate of charoite. Thin section, nicols crossed, x 60. </p><p>Hj4 </p><p>(010) </p><p>FIGURE 2. Optical orientation of charoite. </p><p>If one assumes that the AI2O3 found in analyses 1 and 2 (table 1) is bound to mechan-ical admixtures of anorthoclase, the following formulas of charoite are obtained: </p><p>Anal. 1 - (Ca11)3-35 </p><p>[Si4O10] (OH) 0.52H2O, </p><p>Anal. 2 - (Cai.68Na0436K0.70Sr0&gt;09Ba0.09).,.9, </p><p>[Si4O10] [(OH)0.fllF0&gt;17]0.78 1.00H2O. </p><p>In the formulas of charoite the number of univalent anions is identical ( small differences are explained by the isomorphism of hydroxyl and F ) , very close to their sum ( K + H20), but significantly more noticeable are the dif-ferences of the total contents of univalent - and divalent - cations. These data permit one to assume that in the structure of charoite an in-crease of the content of divalent cations, the K position may be occupied by a molecule of H2O. </p><p>The new mineral differs from the chemically similar canasite ( Ca5Na4K2) n [Sii203o](OH, F) 4, not only by a notable admixture of barium, strontium, and the presence of molecular water, but also by a different total content of cations, and also additional anions, entering into a silicon-oxygen radical (Si4Ol0) - Table 1. </p><p>Comparing the infra-red spectra of charoite and canasite2, from the Khibina Massif (fig. 5), both minerals are observed to show a triplet in the region of the valence oscillation Si-O, thereby for canasite the absorption peaks are of approximately equal intensity, whereas for charoite the low wave-lengths are more intense and the high wave-lengths have minimum intens-ity. The infra-red spectra of the compared minerals also differ considerably in the region 400-800 cm-1, and also in the regions of the hydroxyl oscillation. Canasite has an absorp-tion peak at 3600 c m _ l , but there is not observed absorption in the region of the deformational oscillation of water at 1600-1700 cm-1. This fact permits one to assume that the main part of the water in canasite occurs in the form of OH groups. For charoite, in the region of valence oscillation of hydroxyl there are four peaks: 3410, 3500, 3550, and 3610 cm-1. Be-sides, in the region of deformational oscillation there is observed an intense, slightly resolved triplet: 1590, 1620, and 1650 cm-1. This feature of the infra-red spectrum of charoite permits one to assume that, in distinction from canasite, most of the water in the struc-ture of the new mineral occurs in molecular form, possibly of zeolitic type with different energetic characteristics. </p><p>2Sample 70754 of canasite from the Mineralogical Museum, USSR Academy of Sciences, was kindly pro-vided by M. D. Dorfman. </p><p>616 </p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Uni</p><p>vers</p><p>ity o</p><p>f N</p><p>orth</p><p> Car</p><p>olin</p><p>a] a</p><p>t 16:</p><p>16 1</p><p>1 N</p><p>ovem</p><p>ber </p><p>2014</p></li><li><p>V.P. ROGOVA ET AL. </p><p>TABLE 1. Chemical composition of charoite (1-3) and canasite (1-2). </p><p>Components </p><p>Si02 Ti02 A1203 Fe203 FeO MgO CaO BaO SrO MnO Na20 K20 H2Ot H20" F CI co2 P 2 O 5 </p><p>TOTAL - 0 = F 2 </p><p>TOTAL </p><p>Charoite </p><p>1 </p><p>56.30 </p><p>1.85 </p><p>20.44 3.30 0.90 </p><p>2.45 10.50 3.80 </p><p>99.54 </p><p>99.54 </p><p>&gt; </p><p>56.38 </p><p>1.07 </p><p>20.70 3.12 2.20 </p><p>2.44 8.26 5.13 </p><p>0.75 </p><p>100.05 0.32 </p><p>99.73 </p><p>3 </p><p>56.88 </p><p>0.12 </p><p>20.95 2.52 0.90 </p><p>3.77 10.36 4.40 </p><p>0.92 </p><p>100.82 0.39 </p><p>100.13 </p><p>Canasite, Khibina Massif (Dorfman et a l . , 1959) </p><p>1 </p><p>56.08 0.10 0.55 1.41 0.71 0.05 </p><p>20.95 </p><p>0.38 8.01 8.47 1.11 0.49 2.21 0.22 0.20 0.04 </p><p>100.98 0.96 </p><p>100.02 </p><p>2 </p><p>55.71 0.06 0.20 0.72 0.36 0.26 </p><p>20.39 </p><p>0.41 7.08 </p><p>10.63 1.25 0.60 2.17 </p><p>0.08 </p><p>99.92 0.91 </p><p>99.01 </p><p>Note: Analysts of charoite, K. P. Glebova (anal. 1), A.V. Bykova (anal. 2), N.N. Kuznetsova (anal. 3). </p><p>250 </p><p>S # CO </p><p>"3 </p><p>50 V </p><p>0 </p><p>v-Background Ba </p><p>f4\j Background Sr </p></li><li><p>IMTERNATIONAL GEOLOGY REVIEW </p><p>3800 3400 2000 1600 1200 800 600 400 cm-1 </p><p>FIGURE 5. Infra-red spectra of charoite (1) and can-asite (2). </p><p>100 300 500 700 900 1100 C </p><p>The derivatogram of charoite records sev-eral endothermic effects (fig. 6). Most of the water ( ^ 2 . 4 % ) is lost up to 300 with low, approximately constant velocity. Then in the region 300-600 there is lost ~ 1. 3% (maximum a t~330 ) . From 350 to 1000 there is observed a monotonous loss of weight ( ~ 2. 0%) ,on which there are superposed small endothermic effects with a small loss of water (~440 , 760, and 970). The DTA curve of charoite differs sharply from the heating curve of canasite. Characteristic for canasite is the absence of an endothermic effect up to 900, which agrees with the data of structural analysis (Chiragov et a l . , 1969) and infra-red spectroscopy of this mineral (water in canasite is contained only in the form of OH groups). </p><p>Despite the similarity of composition of charoite and canasite, their X-ray patterns differ sharply (table 2). In order to index the X-ray pattern of charoite and to determine the parameters of its unit cell, the method of elec-tron microdiffraction was used, using a gonio-metric arrangement. </p><p>Considering two microdiffraction patterns of charoite (fig. 7), one can note that one of the periods of repetition of the lattice of charoite coincides with the direction of elongation of the plane of the strip of its microcrystal and equals 7. 13 A. </p><p>The second feature of the electron diffrac-tion patterns is that reflections in them are distributed according to a primitive rectangular motif (fig. 7). Under these conditions, the period of repetition, equal to 7. 13 A, is a s -sumed to be parallel to the elongation of the microcrystal and is the b axis of the lattice of charoite, and the reflections on the "zero" layer line have indexes hOL The periods of repetition in directions perpendicular to the b axis are equal to 31. 7 and 18. 56 A for the elec-tron diffraction patterns represented in figs. </p><p>FIGURE 6. Derivatogram of charoite. 1 - DTG (1/10), 2 - DTA (lrlO), 3 -</p><p>TG (wt. 5.25 mg). </p><p>7a and 7b, respectively. Besides, electron diffraction patterns were obtained with a r e c -tangular grid of reflectioons and the period b = 7.13 and d( hoi) = 13. 3 A. Note that one of the periods listed above corresponded to the mag-nitude d = 31. 8 A of the first low-angle reflec-tion on the X-ray pattern of charoite. It is natural to assume that dioo = 31. 8 A. Because d200 is &lt; 18. 7 A, then the interplanar spacing at 18. 7 A ought to correspond to an index 101. At first the variant was tried with 1 = 1, be-cause with increase of 1, the parameter c in-creases sharply. It was found that with 1 = -1 all reflections could be indexed on the various electron diffraction patterns, if a sin /3Q= 31.7, b = 7. 13, dloi = 18. 5, d20l = 12. 50 A. Later, refinement of the parameters of the unit cell of charoite was made by indexing the powder pat-tern of the mineral (table 2). </p><p>As the result, we obtained a = 31. 82 0. 05, b = 7. 13 0. 03, c = 22. 10 0. 05 A, /3 = 94 15'. It must be noted that the magnitude of the parameter b of the lattice of charoite is very close to the corresponding parameter of such minerals as wollastonite, xonotlite, cana-site, and other calcium silicates. The volume of the unit cell of canasite is nearly exactly one-third that of charoite. It is interesting to compare both minerals at equal volume: </p><p>canasite (Ca30Na24Kj2)s6 [Si7;SOI80 [OH, F)24, charoite (Ca2g-32Na9/16Sr0_54):!8,2 (K l 6 72 HaK 4)17.98[Si72()180l(OH, F)1 4- 13H20. </p><p>The sum of the cations and the molecules of zeolitic water are within the error of cal-culating the coefficients in the formula of </p><p>618 </p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Uni</p><p>vers</p><p>ity o</p><p>f N</p><p>orth</p><p> Car</p><p>olin</p><p>a] a</p><p>t 16:</p><p>16 1</p><p>1 N</p><p>ovem</p><p>ber </p><p>2014</p></li><li><p>V.P. ROGOVA ET AL. </p><p>TABLE 2. Results of calculation of X-ray patterns of charoite and canasite. </p><p>I </p><p>25 70 </p><p>20 10 </p><p>2 10 21 22 </p><p>10 6 </p><p>12 </p><p>16 8 </p><p>8 5 </p><p>30 </p><p>8 16 16 </p><p>100 20 25 85 </p><p>30 10 5 </p><p>50 35 </p><p>14 </p><p>14 12 </p><p>10 2 2 4 </p><p>10 </p><p>10 </p><p>d exp </p><p>31.8 12.45 </p><p>9.8 9.36 </p><p>7.65 7.37 6.18 6.10 </p><p>5.37 5.12 4.86 </p><p>4.57 4.46 </p><p>4.14 3.98 3.90 </p><p>3.70 3.61 3.56 3.348 3.27 3.20 3.134 </p><p>2.97 2.91 2.87 2.79 2.71 </p><p>2.575 </p><p>2.477 2.393 </p><p>2.292 2.204 2.180 2.133 </p><p>1.966 </p><p>1.773 </p><p>Charoite </p><p>Scaled. </p><p>37.72 12.45 </p><p>9.83 9.39 </p><p>7.65 7.35, 7.37 6.19, 6.23 </p><p>6.00 </p><p>5.3...</p></li></ul>