Alabaster is a soft mineral or stone, often used for carving, and processed for plaster powder. Archaeologists and stone processing industries use different words from geologists. The first uses in a broader sense that includes varieties of two different minerals: the fine-grained type of gypsum and the fine-grained type of calcite. Geologists define alabaster only as a gypsum type. Chemically, gypsum is calcium hydrate sulfate, while calcite is a calcium carbonate.
Both types of alabaster have similar properties. They are usually colorful, translucent, and soft rocks. They have been used throughout history especially to carve decorative artifacts.
This type of calcite is also named " onyx-marble ", " Egyptian Alabaster ", and " Oriental alabaster " and is geologically described as one of travertine banded compact or "stalagmitic limestone characterized by a pattern of swirling ribbons of cream and chocolate". "Onyx-marble" is a traditional name, but geologically inaccurate because both onyx and marble have different geological definitions of the most extensive "alabaster" definition.
In general, ancient alabaster is calcite in the wider Middle East, including Egypt and Mesopotamia, while it is gypsum in medieval Europe. Modern alabaster may be calcite but it can be. Both are easy to work and slightly soluble in water. They have been used to make various artwork and carvings in the room, and they will not last long outdoors.
Both types are easily distinguished by their different hardness: gypsum alabaster is so soft that nails scratch it (Mohs hardness 1.5 to 2), while calcite can not be scratched in this way (Mohs hardness 3), even though it produces a knife. In addition, calcite alabaster, to carbonate, is bubbling when treated with hydrochloric acid, while the gypsum albaster remains virtually unaffected when treated so.
Video Alabaster
Etymology
The origin of "alabaster" is Central English through the Old French "alabastre ," which in turn comes from the Latin "alabaster ", and that is from the Greek " ?????? "(" alabastros ") or" ????????? "(" alabastos "). The Greek words symbolize the vase of the alabaster.
The name may be further derived from the Ancient Egyptian " a-labaste ", which refers to the Egyptian goddess Bast, Bast. He is portrayed as a lioness and is often depicted as in numbers placed aboard this alabaster. Other suggestions include the derivation of the name of the ancient city of Alabastron, Egypt, which is described in a way that is sometimes contradicted by ancient Roman writers, e. g. Pliny the Elder on On Stones and Ptolemy at Geography ), unknown location.
Maps Alabaster
Property and usability
The purest Alabaster is a white-coated material of fine uniform grain, but is often associated with iron oxide, which produces brown wrinkles and tendons in stone. The rough variation of alabaster gypsum is converted by calcination into Paris plaster, and is sometimes known as "stone plaster."
The softness of the alabaster allows it to be engraved easily into intricate shapes, but its solubility in water makes it unsuitable for outside work. If the alabaster with a smooth surface, polished washed with dishwashing liquid, it will be rough, dull and whiter, losing most translucent and shiny. The finer types of alabaster are mostly used as decorative stones, especially for ecclesiastical decoration and for stair rails and halls.
Modern processes
Working techniques
Alabaster is mined and then sold in blocks to an alabaster workshop. There they are cut to the required size ("squaring"), and then processed by different techniques: turning a rounded lathes, carved into a three-dimensional sculpture, sculpted to produce low relief figures or decorations; and then given a complicated solution that reveals its transparency, color, and texture.
Imitation Marble
To reduce the translucency of alabaster and to produce the suggestive opacity of real marble, the statues are immersed in a tub of water and heated gradually - almost to the boiling point - an operation that needs great attention, because if the temperature is not carefully regulated , the stone obtained a white appearance of dead, calcareous. The heating effect appears to be partial dehydration of gypsum. If properly cared for, it resembles real marble and is known as "marmo di Castellina".
Immersion
Alabaster is a porous stone and can be "dyed" to any color or shade, a technique used for centuries. For this the stone must be fully immersed in various pigment solutions and heated to a certain temperature. This technique can be used to disguise alabaster. In this way a very misleading copy of a coral called "coral alabaster" is produced.
Type, event, history
Usually only one type is carved in a particular cultural environment, but sometimes both have worked to create similar pieces in the same place and time. This is the case with a small bottle of alabastron made in Cyprus from the Bronze Age to the Classical period.
Panel window
When cut in thin sheets, the alabaster is transparent enough to be used for small windows. It was used for this purpose in Byzantine churches and later in medieval times, especially in Italy. A large piece of albonic dononum Aragon is used extensively in the contemporary cathedral of Our Lady of the Angels, dedicated in 2002 by Los Angeles, California Archdiocese. The cathedral incorporates special cooling to prevent panels from overheating and turns opaque. The ancients used the calcite type, while the modern Los Angeles cathedral uses gypsum alabaster.
Calcite alabaster
Calcite alabaster, harder than gypsum varieties, is the type mainly used in ancient Egypt and the wider Middle East (but not the relief of the Assyrian palace), and is also used in modern times. These are found as stalagmite deposits from the floors and walls of limestone caves, or as a kind of travertine, similarly deposited in calcareous springs. The precipitate in successive layers gives rise to the twisted appearance often exhibited by marble on the cross-section, from which the name is derived: onyx-marble or alabaster-onyx, or sometimes only (and incorrectly) as onyx.
Egypt and Middle East
The Egyptian Alabaster has been mostly done near Suez and Assiut.
These stones are the "alabaster" of ancient Egypt and the Bible and are often called East Alabaster, because early examples came from the Far East. The Greek name alabastrites is said to have originated from the city of Alabastron in Egypt, where the stone was dug. Locality may owe names to minerals; the origin of the mineral name is not clear (though see above).
The "Oriental" alabaster is greatly appreciated for making small perfume bottles or an ointment vase called alabastra; the name of the vessel has been suggested as a possible source of the mineral name. In Egypt, craftsmen use alabaster for canopic jars and various other sacred and seprchar objects. A sarcophagus found in the tomb of Seti I near Thebes is on display at Sir John Soane Museum, London; it is carved in a block of translucent calcite alabaster from Alabastron.
Algerian marble onyx has been excavated mostly in the province of Oran.
North America
In Mexico, there is a famous deposit of the soft green varieties at La Pedrara, in the district of Tecali, near Puebla. Onyx-marble occurs also in TehuacÃÆ'¡n district and in some regions of the US including California, Arizona, Utah, Colorado and Virginia.
Gypsum alabaster
Gypsum alabaster is the softer of the two varieties, the other is the calcite alabaster. It was used mainly in medieval Europe, and is also used in modern times.
Near and Ancient Near Eastern
"Mosul marble" is a kind of alabaster gypsum found in northern modern Iraq, used for the relief of the Assyrian palace in the 9th to 7th century BC; this is the largest type of alabaster statue made regularly. The reliefs are very low and the carvings are detailed, but the large room is coated with a continuous composition on the slab about 7 feet (2.1 m) tall. The Lion Hunt of Ashurbanipal and the Lakhish relief military, both the 7th century and the British Museum, are some of the most famous.
Gypsum alabaster is widely used for small sculptures for indoor use in the ancient world, especially in ancient Egypt and Mesopotamia. Smooth details can be obtained in materials with an attractive finish without iron or steel tools. Alabaster is used for ships dedicated to use in the cult of the god Bast in ancient Egyptian culture, and thousands of alabaster gabsum artifacts dating to the end of the 4th millennium BC have also been found in Tell Brak (now Nagar), in Syria.
In Mesopotamia, the alabaster gabsum is a distinctive ingredient for the gods and worshipers of the temple, as in a figure believed to represent a god, Abu, dating to the first half of the 3rd millennium BC in New York.
Aragon, Spain
Most of the world's alabaster extractions are conducted in the center of the Ebro Valley in Aragon, Spain, which has the world's largest exploitable deposit. According to a brochure published by the Aragon government, alabaster elsewhere has been exhausted, or the extract is so difficult that it is almost abandoned or done at a very high cost. There are two separate sites in Aragon, both located in the Tertiary basin. The most important site is the Fuentes-Azaila area, in the Tertiary Ebro Basin. The other is the Calatayud-Teruel Basin, which divides the Iberian Territory into two main sectors (NW and SE).
The abundance of Aragonic alabaster is very important for use in architecture, sculpture and decoration. There is no possible record of use by pre-Roman culture, so perhaps the first to use alabaster in Aragon was the Romans, who produced ships of alabaster following the Greek and Egyptian models. It seems that since the reconstruction of the Roman Wall in Zaragoza in the 3rd century with alabaster, the use of this material became common in buildings for centuries. The Saraqusta Muslim (today, Zaragoza) is also called "Medina Albaida", the White City, due to the appearance of alabaster walls and palaces, which stand out among gardens, gardens and gardens by the Ebro River and Huerva.
The oldest remains of Aljafera Palace, along with other interesting elements such as the capital, reliefs and inscriptions, are made using alabaster, but during the artistic and economic blooms of the Renaissance the Aragonese alabaster reaches its golden age. In the 16th century sculptors in Aragon chose alabaster for their best work. They are adept at exploiting the quality of the lighting and in general the artwork that has so retained its natural color.
Volterra (Tuscany)
In Europe, the alabaster trade center today is Florence, Italy. Tuscan alabaster occurs in the nodular mass embedded in limestone, intersected with Miocene and Pliocene maros. This mineral works mostly through an underground gallery, in the Volterra district. Some varieties are recognized - veined, spotted, misty, agatiform, and others. The best types, obtained primarily from Castellina, are sent to Florence for sculptures, while the common types are carved locally, into vases, lamps, and various ornamental objects. These items are vast trading objects, especially in Florence, Pisa, and Livorno.
In the 3rd century BC Etruscans used the Toscana alabaster from the modern Volterra area to produce feeding urns, which may be taught by Greek artists. During the Middle Ages, alabaster crafts were almost completely forgotten. The resurrection began in the mid-16th century, and until the beginning of the 17th century fast work was highly artistic and did not develop to form a large industry.
In the 17th and 18th centuries, artefacts of artefacts of high-quality artistic artefacts ceased altogether, replaced by less sophisticated and less expensive items that were more suitable for large-scale production and trade. The new industry is prosperous, but the need for skilled craftsmen is reduced to make only a few still work. The 19th century brought an explosion to the industry, mostly because of the "traveling craftsmen" who went and offered their merchandise to European palaces, as well as to America and the East.
In the 19th century new processing technologies were also introduced, allowing for the production of specially crafted pieces, as well as combinations of alabaster with other ingredients. Apart from the newly developed craft, artistic work becomes possible again, especially by sculptor Volterran Albino Funaioli. After a brief deterioration, the industry was revived by the sale of massively massive expressionist statues, and was further enhanced in 1920 by a new branch that created ceilings and wall lamps in the Art Deco style and culminated in participation in 1925. The International Exhibition of Industrial and Decorative Art from Modern Paris. The important names of the evolution of alabaster use after World War II were Volterran Umberto Borgna, "the first alabaster designer", and later on architect and industrial designer Angelo Mangiarotti.
England and Wales
Gypsum alabaster is a common mineral, occurring in England at Keuper's march in the Midlands, mainly at Chellaston in Derbyshire, at Fauld in Staffordshire, and near Newark in Nottinghamshire. Deposits in all these locations have been done extensively.
In the 14th and 15th centuries, the carvings became small sculptures and sets of relief panels for altarpieces were a valuable local industry in Nottingham, as well as major UK exports. These are usually painted, or partially painted. It is also used for stupas, often life size, in monument tombs, because the distinctive lying position matches with the lack of material strength, and it is cheaper and easier to work than good marble. After the British Reformation the creation of the altar set was stopped, but the burial monument worked on relief and the sculpture continued.
In addition to these examples of engravings still in England (especially at Nottingham Castle Museum, the British Museum, and the Victoria and Albert Museum), alabaster mineral trade (not just antiquities trading) has spread examples in material that can be found so far. afield as Musà ©  e de Cluny, Spain, and Scandinavia.
Alabaster is also found, albeit in smaller numbers, at Watchet in Somerset, near Penarth in Glamorganshire, and elsewhere. In Cumbria it occurs mostly in New Red rocks, but on lower geologic horizons. The alabaster from Nottinghamshire and Derbyshire are found in thick nodular beds or "floors" in spheroidal masses known as "balls" or "bowls" and in smaller lenticular masses called "cakes." In Chellaston, where a local alabaster known as "Patrick," has been worked into an ornament called "Derbyshire spar" - a term more appropriately applied to fluorspar.
Black alabaster
Black alabaster is a rare form of anhydrics from gypsum-based minerals. This black form is found only in three veins of the world, each in the United States, Italy, and China.
Alabaster Caverns State Park, near Freedom, Oklahoma is home to a natural gypsum cave where lots of gypsum is in alabaster form. There are several types of alabaster found on the site, including pink, white, and rare black alabaster.
Gallery
The Ancient Near and Classical Near
Medieval Europe
Modern
See also
Mineralogy
- Calcite - a mineral composed of calcium carbonate ( CaCO
3 ); archeologists and rock trade professionals, unlike mineralogy, call one type of "alabaster" calculus - Gypsum - mineral composed of calcium sulfate dihydrate ( CaSO
4 Ã, Â · 2H
2 O ); alabaster is one of the variations- Anhydrine - a mineral that is closely related to gypsum
- Calcium sulfate - the main inorganic compound ( CaSO
4 ) from gypsum
- Fengite - a transparent marble or alabaster sheet used during the Early Middle Ages for windows instead of glass
- Mineral list
Window panel and roof
Example chronological list:
- Galla Placidia mausoleum - 5th century, Ravenna
- Basilica of San Vitale - 6th century, Ravenna
- Valencia Cathedral - especially the 13th - 14th century, Valencia, Spain; lanterns from the octagonal cross tower
- Orvieto Cathedral - 14th century, Orvieto, Umbria, central Italy
- St. Peter's Basilica - the 17th century, Rome; the alabaster window by Bernini (1598-1680) is used to create "highlights"
- Church of All Nations - 1924, Jerusalem, architect: Antonio Barluzzi. The window comes with painted alabaster panels.
- The Transfiguration Church - 1924, Mount Tabor, architect: Antonio Barluzzi. The Alabaster Roof has been tried.
References
Further reading
- Harrell J.A. (1990), "Abuse of the term 'alabaster' in Egyptology," GÃÆ'¶ttinger Miszellen , 119 , pp.Ã, 37-42.
- Mackintosh-Smith T. (1999), "Moonglow from Underground". Aramco World May-June 1999. [5]
External links
- More about alabaster and travertine , a short guide explaining the different and confusing uses of the same term by geologists, archaeologists, and stone trades. Oxford University Natural History Museum, 2012
- Alabaster Craftmanship in Volterra
- Ã, "Alabaster". The CyclopÃÆ'Â|dia America . 1879.
- Richard Hotchkiss, Alabaster , student paper in geology; page geologist instructor Roger Weller, Cochise College, Arizona
Source of the article : Wikipedia
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