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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

PYRITE


PYRITE (Pyrit—Pyrite—ѕирит) (Dioscorides, P. 50 AD.), from Gk. “pyr”, fire, alluding to its sparking, when it is stroke with steel.

Composition & Properties. Sulfide – FeS2, cubic system. Hardness 6-6.5. Density 5-5.2. Cleavage none. Metal luster. Fragile. In nature pyrite is widespread. It is found as well-formed crystals, their aggregates, grained masses and inclusions in minerals and rocks. The shape of crystals is cubic or more complicated; the size can be rather large. Joint doublets are typical for it. Non-transparent. Color is brass-yellow, sometimes with variegated blueing. It forms pseudomorphs on organic remains. Its crystals and druses are highly valued as collection material. Pyrite, incrusted into rocks and found in schlich, is called fool’s gold. The presence of such inclusions in gem-quality turquoise or lazurite makes their price higher, and in rock crystal or quartzite they produce aventurescence sometimes. Breccia from fragments of pyrite cemented with chalcedony is an ornamental rock with the trade name agate pyrite. An ornamental bluish-white quartzite with brown-red veins and spots of inclusions of cubic pyrite crystals has the trade name eosite.

Deposits. Pyrite is formed at the deposits of different genetic types, but the best collection samples are found in ore veins. In Russia, in the Murmansk Region, at the iron-ore Kovdor deposit, and in Karelia, in metamorphic rocks of the Kiv-Guba, pyrite crystals up to 40 cm. in cross-section were found. In the Novgorod Region, near Borovichy, at the Yasenkovskoye deposit, in black band layers among clays, pyrite exists as concretions and pseudomorphs on fossil wood. In the Volga Region, at the Zakharjevskiy mine near the city of Ul’yanovsk, pyrite forms pseudomorphs on ammonite shells. In the Kursk Region, at the Mikhailovskiy mine, pyrite can be found as stalactites, 10 cm. long. In the Northern Caucasus, in the upper reaches of the Kuban’ River, near the settlement of Ust’-Jeguta, celestine hair stone is found, which is enriched with inclusions of needles of pyrite. In the Middle Urals, at the Berezovskiy mine near the city of Yekaterinburg, well-formed crystals of pyrite reached 18 cm. along the edge of the cube and 35 kg. At pyrites deposits pyrite exists as grained aggregates. In the South Urals, at the Astaf’evskoye deposit, inclusions of pyrite in crystals of rock crystal are typical. In Transbaikalia, at the Kalangui deposit, pyrite forms small-crystal inclusions in ornamental fluorite. In the Primorskiy Region, at Dal’negorskoye deposit, crystals pyrite reach up to 50 cm. along the edge of the cube. In Kazakhstan, at the deposits Aqshataü and Quara Oba (Karaoba), large crystals of pyrite were found. Such crystal from the Aqshataü deposit, 25x18x15 cm. in size, 32 kg., is kept in the Fersman’s Museum, Moscow. At the Sokolovskiy mine, the size of pyrite crystals reached 60 cm. along the edge of the cube. In the Caucasus, in Azerbaijan, at the Paragchai deposit, pyrite is represented in all the variety of shapes of crystals. In Spain, at the deposits Valdenegrillos, Prov. Soria; and Ambasaguas, Prov. de León, well-formed pyrite crystals, up to 13 cm. in size, are extracted as collection material. In Italy, in pegmatites of the Elba Is., at the Rio Marino deposit, the size of crystals reached up to 20 cm. The biggest crystal of pyrite, up to 60 cm. along the edge of the cube, was found in Greece, at the Xánthi deposit, and up to 15 cm. at the Khalkidhikí (Chalcidike) Penin.

In Brazil, at deposits of rock crystal in Minas Gerais State they find transparent crystals of quartz with pyrite as inclusions up to 3 cm. in size. In Peru, at the Huanzala mine, the Uanuco Dept., pyrite crystals up to 20 cm. in size are found in quartz. In the Argentina, at the Santo Mino, Patagonia, pyrite crystals up to 23 cm. in size were found. In the U.S.A., at the deposits Sparta and Ziegler, Illinois, disc-shaped concretions of pyrite are found – so called pyrite suns or pyrite dollar up to 12 cm. in diameter; crystals up to 30 cm. are found in deposits at Leadville, and at the Climax mine, Lake Co., Colorado, also and up to 12 cm. at Bingham Canyon, Salt Lake Co., Utah. On the Prince of Wales Is., Alaska, pyrite crystals up to 4 cm. along the edge of the cube are extracted from cavity (more than 2 m. in size) in diopside-garnet skarn. In Missouri, at the Amex mine, the size of pyrite crystals reached 32x8 cm.

Synonyms. Alpine diamond | Pennsylvania diamond | Sulfur diamond | Eisenkies, Germ. | Grünkies | Kies, Germ. | Marcasite, mist., because marcasite is an orthorhombic analogue of pyrite, in jewelry it isn’t used because of its radial-rayed structure and fast oxidation in the open air | Prismatic marcasite | Liver ore | Iron pyrites | Sulfuric pyrites | Inca stone | Simple stone | Xanthopyrites.

Cut Gems. In jewelry pyrite has been used even in the civilizations of Ancient Egypt and pre-Columbian Central America. In the tombs of Peru, mirrors made from large pyrite crystals were found. In the 18th cent. rose-cut pyrite was in fashion among jewelers under the name of marcasite. Later, insets from polished steel were made under the same name. Pyrite was processed in cabochon as insets for rings and other adornments. Nowadays, pyrite is often set in cheap adornments as whole crystals or facet small “roses”, which surround large gemstones. As insets, also pyrite crusts of small crystals are used. Cabochons of rock crystal with pyrite inclusions are popular among jewelers. Flat discshaped concretions of radial-rayed aggregates of pyrite – pyrite sun from deposits of the U.S.A. – look as natural adornments. Also, pyrite pseudomorphs on fossil wood, shells and ammonites are of jewelry interest. In the Ul’yanovsk Region, Russia, ammonite, replaced with calcite, incrusted with pyrite in inner cameras, are called simbirzit. Slightly polished halves of such ammonites are ready adornments. The most interesting pseudomorph of pyrite was a finding of a medieval miner’s body in one of the Swedish mines near Falun, Dalarnas. All of his body and clothes were replaced completely with pyrite. In museum collections crystals are often infected with tiobacteria, which leads to complete destroying of samples. To avoid it, collectors should process pyrite crystals with antibiotics solution.

Legends. Ancient Mayas treated pyrite as a health stone; a healing effect was connected with it. Astrologers link it with Fire and such planets as Mars and Neptune; they suppose it gives luck to fanatics and desperate people. As a talisman, pyrite is recommended for those, who were born under the signs of Taurus, Sagittarius and Scorpio.

Similarity. Pyrite has similarity with native gold and chalcopyrite.

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