Alabaster

Alabaster is a very common, microcrystalline variety of the mineral gypsum. Chemically, it is located at Alabaster a calcium sulfate. It has visual resemblance to marble, but is contrary to this is a poor conductor of heat. Therefore Alabaster feels warm. Its color may vary by locality be white, light yellow, reddish, brown or gray.

As Egyptian alabaster a variety of calcite called with a similar appearance as the Gipsspat - variety. However, this is in contrast to the gypsum alabaster water insoluble and harder. It is to sinter ( onyx ). The term "Egyptian alabaster " for the processed travertine from the Wadi Sannur and Bosra - Wadi stubbornly persists in archeology.

Etymology and history

The region between Minia and Assiut designated the Egyptians in the Ptolemaic period with the Gaunamen Alabastrites. The obtained there decoration stone, petrographical a travertine and now also known as onyx marble got transferred this word to name him after his origin. Rosemarie Klemm and Dietrich clamping assume that the Romans this term transferred due to similar optical properties to the gypsum rock from around Volterra.

Other theories have been discussed for the origin or derivation of the word alabaster: It is believed that the term comes from the Egyptian alabaster. It could be derived from the Upper Egyptian city Alabastron; Other assumptions are that it originated from the word ἄλαβα alabe (Greek for " without handles "). Another guess is that the origin of the word from "ana (r ) " and the name " Bast ( et ) " is what it means so much, " Stone of the Goddess Bast ( et ) ". She was mystical traditions, according to owner of make-up vessels of alabaster. In a figurative sense, the term denotes a very bright alabaster skin, smooth skin with a silky shine. In the Baroque period was this " alabaster " skin as a beauty ideal of noble ladies.

In late medieval England were in the Midlands, at Tutbury, Staffordshire and later in Chellaston, Derbyshire discovered extensive alabaster quarries. They led to a wide production of tombs, altar pieces, statues and statuettes. The production of devotional objects was suspected in workshops in Nottingham. Recent research has shown, however, that the alabaster objects are created in the vicinity of the quarries, because the raw material consisted of large blocks that had to be appropriately processed locally. The costly transport of the material over the country to Nottingham would the production of objects unnecessarily expensive, especially as the River Trent, which flows near the quarries in the direction of Nottingham, in the Middle Ages was not navigable. The "School of Nottingham ", which the English alabaster production is falsely attributed to the present day, is a legend that the art historian John Hope has 1907 claims because there around 1370 a sculptor for Alabaster is detectable once, but after that no more.

The medieval English devotional objects from Alabaster have mainly preserved in France in the regions that were in the Middle Ages in the possession of the English, in Aquitaine, Normandy and Brittany. In England, even the plants were completely destroyed during the Reformation in the 16th century and the revolution in the 17th century or out of the country managed to occasionally buried. The Alabastergrabmäler for English kings and nobles, but also Come to wealth citizens can be seen in many churches of England today. Outstanding examples are the tombs of Edward II in Gloucester Cathedral and Henry IV and his wife, Joan, in the Cathedral of Canterbury and the three tomb of Margaret Holland, the Earl of Somerset and the Duke of Clarence ibid.

The quarries of the Midlands have been exhausted since the 20s of the 20th century and overgrown with vegetation.

Varieties and modifications

Other varieties of Gipsspat are selenite ( selenite ) and fibrous gypsum.

Education and Locations

Alabaster is in most cases its natural occurrence, a sediment that is produced in large quantities within salt lakes or isolated marine basin in the evaporation of water. This mode of formation can be thought of by the retreat of the sea in the trough-shaped depressions; here often in paragenesis with carbonates, halite and other similar minerals. Depending on the approach, and deposit situation one speaks of a mineral or Evaporitgestein.

Alabaster can, however, arise in sulfidic ore deposits by weathering as sintering deposition or oxidation processes.

Alabaster is composed of calcium sulfate ( gypsum ) and water of crystallization.

Locations for crystals include Romania ( Cavnic ), Poland ( Tarnobrzeg ), Spain ( Gorguel ) and Mexico ( Naica, Chihuahua ). The fine-grained aggregates can be found among others in Italy.

A large mining area is located between Sulzheim and Bad Windsheim in Lower Franconia. There, for centuries gypsum is mined and found alabaster in the form of potato tubers large, which is located as an inclusion in the plaster.

In Alabaster Caverns State Park in Oklahoma is one of the largest, developed as a show cave, gypsum cave in the world with a length of about one kilometer. The walls of the cave are lined with pink, white and the rare black alabaster.

Reduction

The degradation of Alabaster to commercial and artisanal purposes you will find egg-shaped ingots 1-3 meters in length. Also today is still extracted and processed alabaster in Europe. A center of European alabaster is the Italian Volterra, in whose vicinity the rock is already used since Etruscan times.

Use

Because alabaster is much softer than many stones, such as marble, but harder than conventional plaster, he was often used for vases and art objects. Alabaster is suitable for making small decorative objects as well as for life-size sculptures and reliefs. However, he is seen sculptural to the typical interior stones, ie Alabaster is not weatherproof - such sculptures are dependent on protected areas. The material would be destroyed within a few years by the weather. Thinly sliced ​​alabaster is very translucent and is therefore often used in crafts for lampshades. In dry areas such as Central Spain also has use as a church window tradition. Less well known but impressive are the altars of alabaster from the Unterklettgau in Salem Münster.

Table lamp made ​​from Italian alabaster foot

Relief of the Nativity of English alabaster, around 1400, Nottingham

Walls in the Alabaster Mosque in Cairo

Alabaster bowl after Etruscan Volterra model from / Italy

Giuseppe Volpini: Elector Max Emanuel, in 1720, Bavarian National Museum

Alabaster Bowl from Egypt

Alabaster Window in the Moorish palace of the Aljafería, Zaragoza, Spain

12 meters high epitaph Heldburger Alabaster in Morizkirche Coburg for Duke Johann Friedrich the Middle (sculptor: Nicholas Bergner from Heldburg 1596 /98)

The pulpit altar of St. John's Church in Castell from unterfränkischem Alabaster