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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

BITUMEN (HARD)


HARD BITUMEN (Hart Bitume—Ferme bitumes—“вЄрдые битумы). Hard bitumen has been known since the antiquity; they were described by Pliniy the Elder. In comparison with fossil coals, they are characterized with more complicated conditions of formation. The most interesting among them are albertite and asphaltite, as well as solid, graphite-like anthraxolite and shungite. Sometimes, they are used in jewelry – as they are or as varnish.

Albertite (Pinkerton, J. 1811), after the discovery location in the Alberta Prov., Canada. Hardness 2-2.5. Density 1.1. Pitch luster. It is softened under heating. It is hardly dissolved in chloroform. Albertites, or naphtious coals of black color with pitch luster are found as veined accumulations. In Canada, near New Brunswick, Alberta Prov., they discovered a vein of Canadian albertite up to 5 m. thick, 840 m. long. It is used for imitation of jet in manufacturing of cameos and small stone plastics. Among the other albertites in New Scotland (Nova Scotia), they extract stellarite and impsonite. Impsonite of black color with half-dull luster and hardness up to 3, density up to 1.2 is not melted under heating. In the U.S.A., albertite is found in the form of veins up to 3 m. thick – in Arkansas and Oklahoma. Its findings are also known in Peru.

Asphaltite (Blake, 1890), from Gk. “asphaltos” – resin. Hardness 2-2.5. Density 1. The temperature of melting 100-130°C, it is soluble in chloroform. It is from the group of pyrobitums – products of the transformation of petroleum. It is found in the form of veins and bedded deposits, sometimes of significant thickness. Ornamental variety of asphaltites is gillsonite or uintahite.

In Russia, black gillsonite with diamond luster was found in Komi Rep., on the Izhma River, near Ukhta – ukhta gillsonite. In the U.S.A., it is found in the Utah State. In the south-eastern part of Turkey, near Aksu (Harbul) and Avkamasya, Sirnak vilayet., veins of hard bitumen are up to 3500 m. long, up to 20-80 m. thick, and the dip of veins is up to 500 m. depth. This bitumen is used in jewelry in the place of jet.

Synonyms. Asphaltite – Bergpech, Germ. | Gillsonite, after Gillson, who organized its extraction in the Utah State, the U.S.A. | Mountain resin | Uintahite, after the discovery location in the valley Uintah, Utah, the U.S.A. | Velikhovite, after the discovery location near Velikhovo, South Ural, Russia.

Anthraxolite (Chapman, E.J. 1888), from Gk. “anthraxos” – coal and “litos” – a stone. Hardness 3-4. Density 1.3-2. Pitch luster. It is not melted, not soluble in chloroform, hardly burnt. It is a hard carbonaceous compound, composed on 90-98% with carbon. It is found in the form of crusts and insets in quartz and calcite-dolomite veins and as inclusions in minerals. In Russia, on the South Is., Novaya Zemlya, lenses of anthraxolite were discovered in quartz veins in the region of Kostin Shar. In the Subpolar Urals Mts., at the Kozhim River, and in Nothern Urals, they found graphitized anthraxolite in the form of crusts, spherical and stalactite-like formations in crystals quartz. In the Ukraine, in pegmatites Volhynia, hard bitumens are as needle aggregates kerrite. In Crimea, inclusions hard bitumens up to 1 cm. and veins in effusive rocks were found in the regions of Simpheropol’, Yalta and others. At first, anthraxolite was discovered in Canada, as veins in Cambrian schist’s in the region of Superior Lake. At the Sudbury deposit, they found it in a quartz vein, which broke black schist’s. At emerald mines of Colombia, inclusions of anthraxolite are observed in crystals of parisite.

Shungite, after the discovery location by the village of Shunga, on the bank of Onega Lake, Russia, where it is found in the form of veins in shungite slates. Non-transparent. Black in color. Metal luster. Hardness 3.5-4. Density 1.8-1.9. Fragile. Essentially it is a high metamorphosed anthraxolite, adequate to amorphous carbon in the composition. They made faceted stones from it for collection purposes, up to 1 ct. in mass, as well as cabochons. Shungite slate of carbonaceousclay composition was used alas well as an ornamental stone. They manufactured carved products from it for common day purposes and used it in mosaics and decoration of interiors. To the northeast from Kondopoga, near the railway station Kivach, they explored the Nigozero deposit of shungite slates. This rock is easy processed and well polished. It is used in interiors of St Isaac Cathedral in St Petersburg.

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