Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia



PETRIFIED WOOD (Fossiles Holz—Fossile l’arbre—ƒерево окаменелое) Here also natural wood is described, which is used in jewelry, too.

Properties. Hardness 5.5-6.5. Density 2.6. In fossil petrified wood organic substance is replaced with mineral components. It is of the group of floragenic jewelry-ornamental materials. In carbonized varieties of petrified wood, replaced with carbonates, hardness is 4, and replaced with quartz it is close to 7. It can be polished like a mirror. Usually petrified wood is replaced partly or completely with minerals of the group of quartz, preserving the pattern and elements of structure of timber – silicified wood. More rarely marbleized wood is found, which is replaced with minerals of the class of carbonates – calcite, dolomite, siderite. There are separate deposits, where replacing minerals are actinolite, baryte, jet, gypsum, pyrite and volkonskoite. Besides, there are known more than 60 other materials taking part in the composition of petrified wood. In the process of replacement structure of timber and all the elements of its structure are kept. It gives special beauty to petrified wood as an ornamental stone, and its property to the well polished and diversity of colors make it one of the most popular kinds of jewelry-ornamental rough material. Color of petrified wood is from gray to reddish-brownish, rose, light brown, yellow and even light blue, blue and violet. It is non-transparent to translucent at the edges.

Deposits. Petrified wood is found usually in the form of complete trunks, buried in sedimentary or volcanic layers. However, the most perspective for extraction are its accumulations at placers.

In Russia, in clay sediments sections of the Novgorod Region, near Borovichi, fossil wood is completely replaced with pyrite. In the Kirov and Vologda Regions there are finds of high quality of a fossil wood: at the Lubyaniki village and Tot’ma localities. In coal basins of the Urals – near Vorkuta, Kizel and in the Chelyabinsk Region, they found black coalification wood replaced with carbonates. In the Preduralia Territory, in sedimentary sections by the localities of Efimyatka and Karavashek Mt., Perm’ Region, petrified wood is replaced with the chrome analogue of nontronite – green volkonskoite, which forms pseudomorphs (phitomorphs) on the tree trunks – “volkonskoite trees”. In the Ul’yanovsk Region, in sedimentary rocks petrified wood has silica-marly composition with stripped, partly brecciated texture. This ornamental material is used as an ornamental stone under the trade name sengelit. Large fragments of petrified wood were found at river placers along the Lena River near Zhigansk; tributaries of the Vitim River. On the Yukhtukon River, a tributary of the Podkamennaya Tunguska River, they found trunks of petrified wood up to 2 m. long. In the Amur Region, at the Uganskoye deposit, in the southern part of the Zeya Reservoir, findings of petrified wood in the form of trunks up to 30 cm. were made together with jasper. Another group of deposits of petrified wood is situated in the low stream line of the Bureya River along the Transsiberian railroad. In the Khabarovsk Region, at the Siziman deposit, petrified wood is characterized with alternation of white, beige and brown layers. In the Primorskiy Region, at the Kurdyumovskoye deposit, in petrified wood light gray and cream colored layers is dominating. On the Chukchi Penin. they find petrified wood replaced with siderite, and Kamchatka at the Makarovskoye deposit – with jet.

In Armenia, petrified wood is known in sedimentary and volcanic rocks. Near Gjumri (form. Leninakan), in tuff-sandstones and tuff-conglomerates, the Sariarskoye deposit of petrified wood is situated. Its trunks are replaced with the mixture of opal and chalcedony, their size is not more than 1 m. long and 0.6 m. in cross-section. Color of petrified wood is polychromatic, stripped-spotty one. At the Kirginskoye deposit, it is replaced mainly with opal. At the Khikoyanskoye deposit, wood is black, because it was coalification and replaced with opal and calcite. In 1911, in Georgia, during the construction of the road from Akhalcikhe to Batumi, on the Goderdzskiy Pass, they discovered a deposit of petrified wood in volcanic tuff, with trunks up to 0.7 m. in cross-section. The composition of this petrified wood included opal and opal chalcedony. Its color was grayish-white, brown of different tones to red as sealing-wax. In the Ukraine deposits of petrified wood replaced with opal and chalcedony are known in the L’viv Region as well as in some other regions. Near L’viv fragments of petrified wood reach 1.5 m. long and 0.5 m. in cross-section. Their color is fair – rose-brown. In Crimea, at the Beshuyskiye Kopi, in coal-containing sediments trunks of conifers are completely coalification and partly are composed with solid jet. In Kyrgyzstan, near Osh, at the deposit petrified wood is completely composed with chalcedony of small and large-spherule structure. In South Kazakhstan, in the Jambul Region, at the deposits Tuzkul and Chabakty, they found silicification trunks up to 2 m. long and up to 1 m. in cross-section, with veins of barytocelestine. In Mongolia they researched such deposits of petrified wood as Erdene Zogt Obo and Alag Uul.

In the U.S.A., there is the Petrified Forest National Park Arizona, near Hollbrook, Apache Co., its age is about 200 million years. Trunks of petrified pines of the kind of Araucaria are replaced with chalcedony and reach 65 m. long and 3 m. in cross-section. Petrified wood of these trunks is beautiful in color and decorated with black dendrites of manganese oxides. Since 1906, this deposit has been declared a national park. However, the biggest trunks of petrified wood were found in Idaho, at the Challis deposit, where in volcanic ash trees up to 7 m. high and 3 m. in cross-section were discovered. In the Washington State, at the Saddle Mountain deposit, they extract cypress petrified wood of beautiful color. In the west of the North Dakota State there is a deposit of petrified wood, too. One more unique Petrified Forest is known in the Argentina, in Patagonia, there is Cerro Cuadrado Petrified Forest, Neuquén Prov. They found interesting chalcedony pseudomorphs on cones of Araucaria there. In Czech Rep., they find fossil trees of the kind of Araucaria with preserved specifics of their structure. Their petrified wood with white spots, called starstone, is used in adornments. Deposits of petrified wood are known in other countries, too.

Synonyms. Wood agate | Cardiolite | Dendrolith | Lithoxylite (lithoxyl) | Devil oak | Wood opal | Sengelit, after the discovery location by the village of Sengeley, Ul’yanovsk Region, Russia | Starling stone | Wood stone | Fossil palm tree | Volkonskoite, after the Russ. minister P.M. Volkonskiy (1776-1852) | ~ wood: Adamic ~, agatised ~, fossil ~, opalized ~, palm ~. | Xylonite, from Gk. “xylon” – wood and “lithos” – a stone, syn. | Xylopal, pseudomorph opal after wood.

Treatment. Petrified wood was used in adornments in Ancient Rome and in ancient states of Mesopotamia. From large trunks they made basal slabs for tables and holders, for caskets and different large objects. So, in 1866, at the Kolyvan’ lapidary factory, they made a desk set from petrified wood in the shape of village huts in the Russian style. In the Mining Museum, SPb., there is a pair of tables from Arizona petrified wood and a trunk of petrified wood from the Kirov Region with a hollow, which is covered inside with crystals of amethyst. Petrified wood is cut in cabochon for jewelry purposes; it is used in stone carving and in the Florentine mosaic. In Canada, petrified wood is a symbol of the Alberta Prov.

Natural wood is a bioorganic formation of the group of floragenic ornamental materials. Here we describe following kinds of wood, the most often met in jewelry: Karelian birch, ebony wood, bog oak, or fine oak, burl nut, bass wood, black and rose-wood, box-tree, fernambuk, sandal, poplar, Brazil wood and others. Among the ornamental materials under the name vegetable ivory they classify: tree coconut , coroso nut, peach nucleus, palm seeds, nut shell and others. Some kinds of wood are used in jewelry for adornments, small plastic, caskets, beads, bracelets, where wood can be used in the combination with stone or just as it is. In the Grün. Gew., Dresden, Germany, there is many samples of usage of natural wood in adornments by Old Germ. masters. There are boxes for jewelries and caskets from ebony wood and nut wood, decorated with gold and enamel, and with encrustations from nacre; figures cut out from box-tree, bass wood and ebony wood.

Vegetable ivory – it is pith of some palm-trees, which are characterized with high level of hardness and density. It is used as material for imitation of ivory. As an example we can mention a palm, which is growing on the Solomon Iss. and in Malaysia; it gives up to 200 nuts with stones up to 6-8 cm. and 0.5 kg. On the Philippines and in Myanmar, such palms produce a plenty of nuts with stones up to 1.5 cm. Palms of the Seychelles give the biggest nuts up to 15 kg. and 40 cm. in cross-section. Coconut trees and similar palms which are widespread in tropical regions have hard nuts with solid peel, which has been used for manufacturing of adornments and carved produce since long ago. In India, coconuts is nut shell, up to 5 cm. thick is gray, brown or black in color, sometimes with obvious stripes. It is used for manufacturing of small adornments. The similar is palm nut ivory of South American ivory palm; Carolina nut ivory from the Carolina Iss., Micronesia; vegetable palm ivory from South Africa and Indian dum-palm, which timber is used for manufacturing of buttons and inoculums for cultured pearls. In the Grün. Gew., Dresden, Germany, there is gilded bowls from tree coconut, including those mounted in gilded silver, made by Germ. masters about 1600. In Colombia, Peru and Ecuador, they use dum palm nut, corozo nut and nuts of other palms for the same purposes. Coroso nut is about a chicken egg in size, after a while it gets harder and they use it for imitation of ivory. On the yellowish surface of these nuts points and small lines are seen.

Bog oak is almost petrified, hard timber, which is extracted from peat bogs. It displays deep dark brown color and can be polished only with big difficulties. It looks like jet, but it is more solid. In the 19th cent., in Ireland, it was used as an ornamental material for carving; that time on natural adornments were very popular. The early of this trade in Ireland is dated to 1821. The King George IV has received a cane, intricately cut out from bog oak, as a gift. Different adornments from this material were fashionable at that time: necklaces, ear-rings, brooches and souvenirs. Since the end of 1860, hand-made carving has been being replaced step by step with stamp carving.

Carvers and jewelers of the firm of K. Fabergé, beside stones and precious metals, used Karelian birch, black and rose wood, burl nut, Brazil wood and other. The Ural jeweler V.M. Khramtsov (b.1932) brightly uses peach nucleus as well as black wood in combination with ivory, obsidian or titan in his produce.

Synonyms. Vegetable ivory – Carolina nut ivory, after the place of collecting on the Carolina Iss., the Philippines Sea | Vegetable palm ivory.