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Home , Chara (river), Charoite, Frankamenite

- A Champion among Mineralogical Discoveries in the Second Half of the 20th Century

V.A. Solyanik ([email protected]), V.A. Pakhomova, M.A. Ushkova Far East Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Vladivostok,

世上唯一被發現的查羅石礦床位於西伯利亞 cummingtonite schists. Cummingtonite 東部近 河附近。查羅石含40種以上 is a magnesian amphibole and, as it was 稀有礦物，十多種花俏的顏色。作者檢測了 later to be proved, charoite contains almost 多顆不同的查羅石，並對其特徵和查羅石的 no magnesium. Twenty years later a new 歷史加以描述。 generation of geologists visited the site, among them a young couple, Vera P. and Yuri G. Rogovs. Their names are closely bound up with the history of the discovery The world’s only deposit of charoite (the of charoite and its investigation and also of Sirenevy Kamen deposit) was found in its accompanying , most of which Eastern near the River Chara. A were unknown at that time. The place where combination of its unusual colour charoite was first discovered is located at and its flamboyant pattern makes a deep the boundary of the and impression on the viewer. Finely laminated Republic (Yakutia), an area of about charoite crystals are intertwined producing 10 km2. the stone’s flowing pattern resembling satin flower petals and intricate swirls that look Charoitite is formed at a contact of like a chatoyant piece of lilac silk. potassium-rich alcaline trachyte-syenite massif and carbonaceous rocks attributed Charoite is an alkaline calcic silicate of a by a number of researchers to carbonatite. complex composition (crystal-chemical Such places demonstrate widely manifested

formula K(Ca,Na)2Si4O10(OH,F)H2O) named potassium metasomatism that has had a after the place where it was discovered, the genetic influence upon the formation of a basin of the Chara River. number of potassic-calcareous silicates – charoite, , and . The history of the discovery of charoite Geologically, the charoitite deposit is Charoite-containing rocks (below referred confined to the southern exocontact of the to as - charoitite) were first found among Murun alcaline Massif characterised by metamorphic and terrigenous-carbonaceous its potassium specialisation. Analogous strata of the Chara Block in 1948 (in in their composition, massifs are rather the western part of the Aldan Shield) by rare worldwide and are known only in V.G. Ditmar, who mistakenly called them Australia, the USA (California), and the

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P077-E7-20081202-v3.indd 77 2009/1/2 9:07:56 PM island of Corsica in Europe. All the massifs K3Na3Ca5(Si12O30)F3(OH)H2O, as well as of this group are characterised by their other less rare minerals. Among the other high alkaline content, which, as a rule, minerals of the Sirenevy Kamen’ deposit,

is significantly higher than its alumina stisiite ThCaSi9O20 is also worth mentioning.

content, with K2O exceeding Na2O, as Due to its composition, thorium makes well. In addition, the Murun Massif’s rocks both the mineral itself, and its host rocks and accompanying mainly metasomatic radioactive [3]. This should be taken into formations located in the massif’s periphery consideration in the production of charoite are characterised by their higher contents of and carvings. At the very least, Ba, Sr, Ti, Zr, and Th. This, in turn, results the mineral should be examined visually to in the presence in their composition of a check for the presence of short prismatic number of rare minerals most of which are grains varying in length from 1 mm to also newly discovered and occur only in the 1-2 cm in different shades of yellow. Such charoite mineralisation zone. isolated minerals are usually ringed with a light brown rim testifying to radioactive Tinaksite NaK2Ca2TiSi7O19(OH) was the disintegration. first mineral discovered at the Sirenevy Kamen’ deposit. It forms as randomly By now, the mineral composition of scattered honey-yellow crystals, sometimes charoitite has been investigated sufficiently grouped in radial-beam aggregates and more than 40 new and often extremely [5]. Charoite was the second. It can be rare minerals (encountered only in two or considered a champion among the minerals three places globally) have been discovered discovered in the twentieth century, as no at the deposit over the past 30 years. other mineral was found in such quantities during this period. At first, the discoverers Charoitite has dozens of fancy varieties of charoite tried to find its analogues characterised by a wide range of colour, among already known minerals. Canasite mineral composition, and structural features that influence the rock pattern and (Ca5Na4K2)1][Si12O30](OH,F)4 discovered in 1959 by M.D. Dorfman in Khibiny was strength [1, 6]. Macro- and microscopic the most similar, however, more detailed investigation of the Museum Collection, investigations of charoite demonstrated their about 40 charoitite-containing samples at differences. Only over fifteen years later, The Museum of Minerology and Geology, in 1977, was charoite proved to be a new enabled us to examine both their structure mineral in its own right and Vera Rogova and decorative properties. was credited with identifying this beautiful Thin-sections revealed the presence of mineral [4]. charoite, aegirine, fedorite, microcline, Further investigation of charoite-bearing tinaksite, carbonate, canasite, apophyllite rocks resulted in the discovery of tokkoite KCa4 [Si4 O ]0] 2 F-8H2 O , p e c t o l i t e NaCa Si O (OH), and single grains of ore K2Ca4Si7O17(O,OH,F)4 — a silver-brown 2 3 8 mineral named after the basin of the Tokko minerals. Aegirine occurs in almost all River [2] where it was found, varieties of charoitite; canasite in pale- colored samples.

78 The Journal of the Gemmological Association of Hong Kong

P077-E7-20081202-v3.indd 78 2009/1/2 9:07:57 PM Uniformly colored lilac charoite, with a pit mine. Charoite resources are estimated compact beam and columnar structure, is at some tens of thousands of tons, with the most attractive. Beam charoite (Fig.1) stone quality varying widely from sample is composed of sheaf-like, differently to sample. Thus, for the moment, charoite oriented aggregates of 5-10 mm in size, of remains the rarest and the most exotic gem a deep lilac colour and with strong pearly stone on earth, and finding an analogous iridescence. This variety contains fewer deposit is still unlikely, even globally. mineral admixtures (up to 15%) and represents high quality jewellery material. This research was supported by the Russian Foundation of Base Research (grant No Samples of spotty-beam charoite 08-05-12029) demonstrate the widest range of colour varieties. The deep purple and lavender background emphasises contrasting spots References: 1. Chiragov M. I., Shirinova A. F. (2004) of black aegirine aggregates, golden or The Crystalline Structure of Charoite as brown-yellow tinaksite, and round spots of a Derivative of Miserite, Canasite and dark green . Beam aggregates can Okenite. (Russian with English abstract): reach up to 3 cm in diameter with spotty Mineralogical Journal (Ukraine). 26(4), beam charoite up to 2-4 cm in diameter. pp 5–9. Spotty-beam charoite is remarkable for its “landscape” varieties (Fig.2) and is used as 2. Lazebnik K.A., Nikishova, L.V., Lazebnik a semi-precious stone. Y.D. (1986) Tokkoite – A New Charoitite Mineral. Mineral. Journal. No 3. pp 85-89 (in Wavy-fibred charoite’s pattern is formed by Russian). discontinuous sub-parallel brown-lilac fibres and cream-coloured streaks (Fig.3). Slatey 3. Nikishova, L.V., Lazebnik K.A., and charoite is characterised by a relatively Lazebnik Y.D. (1985) The Crystal Chemical monotonous violet colour and its slatey Formula of Charoite. Kristallkhim. Strukt. structure is due to its parallel fibres (Fig.4). Tipomor.zm Mineral., pp 100-104. (in Their pearly iridescence is weak. Wavy- Russian). fibred and slatey charoites are also used as semi-precious stones. The Augen variety is 4. Rogova, V.P., Rogov Y.G., Drits V.A., and characterised by a micro-curly structure: Kuznetsova N.N. (1978) Charoite - A New long-fibred curled aggregates of charoite Mineral and a New Jewellery Stone. Zap. associated with carbonate are enveloped by Vses. Mineral. Obshch., 107, pp 94-100 (in grainy or short-fibred charoite (Fig.5). Russian).

By now, gem quality charoite is almost 5. Rogov Y.G., Rogova V.P., Voronkov mined out at the deposit and the state A.A., Moleva V.A. (1965) Tinaksite enterprise “Vostokkvartzsamotsvety” NaK2Ca2TiSi7O19(OH) – A New Mineral. (Yakutia) intends to raise about 1 billion Doklady SA of the USSR. V. 162, No 3. roubles for the construction of an open- pp 658-661 (in Russian).

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P077-E7-20081202-v3.indd 79 2009/1/2 9:07:57 PM 6. Soboleva T.V., Smirnova A.A., Soboleva A.A. (2003) An Estimation of Gem Quality Charoite and its Varieties Used in Jewellery. VI International Conference “, Gemmology, Art”. SPb. pp 69-70 (in Russian).

The Specimens shown are from the Museum Fig. 3 T h e p a t t e r n o f w a v y fibred charoite (16×8 cm) Collection of the Murun Massif, Chara River, Sirenevy Kamen’ deposit, Sakha Republic (Yakutia), Russia.

Fig. 4 Slatey charoite (11×8 cm)

Fig. 1 The polished surface of a sample of a deep lilac charoite of a compact beam structure with strong pearly iridescence. (13×8 cm)

Fig. 5 Augen Charoite (16×11 cm)

Fig. 2 Spotty-beam charoite, Fig. 6 Charoite specimens and carvings “landscape” variety (9×9 cm)

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