Jet (lignite)

Jet is impregnated by bitumen Humusgel or fossil wood, which is in a state of transition from lignite to hard coal.

Etymology

The German jet name is derived from a source in the vicinity of the river and the city Gaga in Lycia (Turkey). It is believed that the English and the French term ( Jetstone or Jais ) is based on this word relatives. It is also referred to as a jet (t) or Black Amber. The latter name is due to the erroneous, but over a long period of persistence of the adoption of various authors of earlier centuries, jet had the same origin as amber. Equally misleading is the term Olti Amber for jet from the Turkish province of Erzurum. Further, some obsolete synonyms are Gayet or Jayet, pitch coke, black stone, Agtstein, Ambranoir and widow stone and Succinum nigrum and Gagatit.

Formation and properties

Jet is often referred to as Sapropelit. In fact, it is at Sapropeliten but generally petrified sapropel sediments that have formed in shallow waters, while jet is the result of the absence of air ( in the digested sludge ) lithifiziertem wood harvested frequently by a large Jurassic Schuppentannenart (Araucaria ). The density of jet (1.23 g / cm ³). Due to its chemical composition (C, O, H, N) it belongs to the coal rocks. The Mohs hardness of the amorphous material is between 2.5 and 4, his break is conchoidal, the stroke color brown to black. As Bernstein also invites jet to electrically when it is rubbed. Because of its velvety fat gloss, can be enhanced by polishing jet is also used as a gemstone.

History

Because of the splendor and light Schnitzbarkeit jet has been used since prehistoric times as jewelry. Also the small stylized female figures of the Magdalenian are pendent. On Peter rock this Venus statuettes jet, a fossilized wood, were produced in large numbers. Only in 1990 have been discovered in the same old dated reference Monruz on Lake Neuchatel in Switzerland almost identical Gagatfigürchen. Gagatgehänge with Amber slides are known. The Romans established jewelery, spinning equipment ( spindle whorls and distaff ) and amulets from her jet. From the Middle Ages, made ​​in Europe from mourning jewelry and rosaries.

Pliny the Elder wrote the jet to healing properties. So he protects her from the evil eye, pastimes snakes, heal hysteria, toothache, defeat the epilepsy and help in the determination of virginity. And in gemstone therapy jet is considered mourning stone.

At the end of the 19th century, the heyday of the Jett - fashion, as the deposits were rare, was also Ebonite, hard rubber, used as jet replacement. The main occurrence was at that time on the English north coast near the port town of Whitby. Other deposits are found in the Spanish region of Asturias (Villaviciosa ), Southern France, Austria ( Gams and Reichraminger Hintergebirge - On Sandl ) and in Württemberg.

The Spanish findings were to a large extent (los azabacheros de Santiago cofradía de ) to the guild of Gagatschnitzer of Santiago de Compostela, the fact that against next jewelry and devotional pilgrim badges and souvenirs in the form of scallops or the so-called Santiago Fica, as a defense the evil eye was, manufactured. The concentration of Gagatschnitzer for a place in the Cathedral of Santiago de Compostela is preserved with Plaza de azabache or Azabachería ( Gagatplatz ) on its behalf.

Imitations

Since the jet rare Onyx resembles, he is partly used as a raw material for imitations thereof. In the meantime, however, it increasingly colored agate and tourmaline serve as a basis for imitation onyx and also for the jet, as this is due to its low Mohs hardness from 2.5 to 4 very sensitive to damage (especially scratches).

Can be confused and imitates jet with anthracite coal, asphalt, Kännel or Sapropelkohle and colored glass, hard rubber and plastic.

• See also: Gem # manipulation and imitation