Other: Petrified wood

Diagnostic card.

Shingonia amorphous
Hardness 5-7
Specific weight 1.9-2.5
Cleavage is absent
Cracked shell
Color different
Color in powder white
Wax gloss

The okremnennoe tree consists of a mixture of minerals of silica - opal and chalcedony, less often quartz - in variable proportions, opal predominates ("wooden opal" - pseudomorphs in wood). It is a fossil, a tree turned into stone, as amateur collectors say, because the organic components of a tree never turn directly to stone, but are removed, replaced by silica with the formation of pseudomorphs.

Fossils are well preserved only in those cases when trees or their parts immediately after dying quickly become buried, overlapping with fine-grained sediments. Then, the circulating water gradually dissolves and takes out the organic constituents of the wood, replacing it with mineral substances, hence, there is not a transformation but a substitution. Sometimes it runs so slowly that the elements of the internal structure of the tree - the annual rings, the structure of the cellulose, even the larval movements - are inherited by the pseudomorph of silica. On the other hand, in the process of silicification there are completely new patterns. The color of pseudomorphs is usually unattractive, gray or brown, but sometimes it is soft red, pink, light brown, yellow or even blue, to blue and violet. Grinding and polishing emphasize the color, making it more juicy.

Okremnevshaya wood, used as an ornamental stone, opaque or slightly translucent. Its color varies from gray to chestnut, even red, and yellow, pink and purple. Wax gloss. In some samples, it is possible to observe (along the elongation) the typical fibrous structure of wood and concentric rings on a perpendicular cut.

Origin.
Changes resulting in the formation of silicified wood occurred over a period of time from two centuries to millions of years. During these periods, forests were exposed to various natural disasters.

Fallen trees were transported by the strongest floods and were buried very far from the place of growth. Their trunks were covered by thicknesses of precipitation reaching hundreds of meters of power. The silicon enriched water circulating in this medium led to the formation of pseudomorphs when the carbon (the main element of the organic matter) was replaced by silicon.

Pseudomorphs were formed due to dense microcrystalline quartz (diaspore), microcrystalline fibrous quartz (chalcedony), and amorphous hydrated silica (opal).

Place of Birth.
The most famous place where such fossil trees are found is the "petrified forest" in Holbrooke, Arizona (USA). There are fossilized araucaria trunks up to 65 m long and up to 3 m in diameter. On the cut, the structure of the tree is read through the alternation of red, yellow, purple and chestnut shades. In another deposit, in Virginia Valley (Nevada), the silicified wood is developed as a raw material for art products of various types.

Small deposits are found in other countries, for example, in Egypt, Argentina, Uruguay and France (Mount Auvergne). In Italy, there are deposits of silicified wood in South Sardinia.

The most famous deposit in the world is the famous petrified forest near Holbrook in Arizona (USA). Here, an accumulation of fossilized tree trunks - pine trees of the genus Araucariae, up to 65 m long and up to 3 m thick, was found. About 200 million years ago, these logs brought here from different places, and then they were covered with a thickness of several hundred meters of rainfall. Over time, the weathering processes released part of the silicified logs and their debris from the surrounding rocks. Nowhere else in the world does a fossil tree have such gorgeous colors, as in Arizona. In order to preserve this unique natural site, the area was declared in 1962 by the National Park Petrifield Forest ("Petrified Forest").

Smaller deposits of petrified wood are found on all continents. Materials of good quality are supplied by Egypt (Jel-Mokaam near Cairo) and Argentina (Patagonia). Pieces of Silenced Wood from Virginia Valley (Nevada, USA) demonstrate a beautiful opal game of flowers. Petrified wood is used mainly for the manufacture of stone-cutting art objects and decorative products (table-tops, ashtrays, book stands, paperweights), less often for jewelry purposes.

In the CIS, a petrified tree is found in Western Ukraine (near Lviv) and in the Transcaucasus (the Goderdz deposit in Adjara, the Sariar deposit in Armenia), the Urals and South Kazakhstan, Kamchatka and Primorye.

Application.
Fossil wood is widely used in jewelry for beads and cabochons. Some of its differences are very popular among collectors.

Species.
Gagat - a dense variety of brown coal - fossilized wood of coniferous trees, common in Europe about 180 million years ago. It is an opaque material, intensely black in color, exceptionally light and soft. Its most significant deposits are in England, in the Whitby zone, in southern Yorkshire. It is also known in France, Germany, the United States and Russia. From the gagata in the jewelry business, they make beads, they process facets or cabochons. It is also used to perform intaglio.

Gagat received its name on the river in South-Western Turkey. This is an organic product - bituminous coal, well-polishing. Characteristic velvety waxy luster, sometimes there are inclusions of pyrite. Electrified with friction. Production areas: formerly England (Whitby in Yorkshire), now Spain (Asturias), France (Dep. Odd), USA (Utah, Colorado). It is processed on a lathe. Used in mourning, for making beads, decorative objects and gems. Imitated by other types of coal (anthracite, kennel coal), glass, ebonite, onyx.

Keinelsky coal (kennel) serves as a substitute for the jet. The name comes from the English candle - a candle, because from the wax extracted from such coals, used to make candles. Kennel coals lie together with coking coal. They are well-lit, rich in volatile components (formerly, they received a light gas). They consist mainly of spores and pollen of plants. Due to its uniformity and durability, the kennel is well processed on a lathe by ordinary joinery tools; Polishing gives it a strong shine.

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