Alabaster is a soft rock used for carvings and as a source of plaster powder. Archaeologists, geologists, and the stone industry have different definitions for the word alabaster. In archaeology, the term alabaster includes objects and artefacts made from two different minerals: (i) the fine-grained, massive type of gypsum, and (ii) the fine-grained, banded type of calcite.More About Alabaster and Travertine: Brief Guide explains the different definitions used by geologists, archaeologists, and the stone trade. Oxford University Museum of Natural History, 2012,
Chemically, gypsum is a hydrous sulfate of calcium, whereas calcite is a carbonate of calcium. As types of alabaster, gypsum and calcite have similar properties, such as light color, translucence, and soft stones that can be carved and sculpted; thus the historical use and application of alabaster for the production of carved, decorative artefacts and objets d’art."Grove": R. W. Sanderson and Francis Cheetham. "Alabaster", Grove Art Online, Oxford Art Online, Oxford University Press, accessed 13 March 2013, subscriber link. Calcite alabaster also is known as onyx-marble, Egyptian alabaster, and Oriental alabaster, which terms usually describe either a compact, banded travertine stone or a stalagmitic limestone colored with swirling bands of cream and brown.
In general, ancient alabaster is calcite in the wider Middle East, including Egypt and Mesopotamia, while it is gypsum in medieval Europe. Modern alabaster is most likely calcite but may be either. Both are easy to work and slightly soluble in water. They have been used for making a variety of indoor artwork and carving, as they will not survive long outdoors.
The two types are readily distinguished by their different hardness: gypsum alabaster (Mohs hardness 1.5 to 2) is so soft that a fingernail scratches it, while calcite (Mohs hardness 3) cannot be scratched in this way but yields to a knife. Moreover, calcite alabaster, being a carbonate, effervesces when treated with hydrochloric acid while gypsum alabaster remains almost unaffected. Endnotes: M. Carmichael, Report on the Volterra Alabaster Industry, Foreign Office, Miscellaneous Series, No. 352 (London, 1895) A. T. Metcalfe, "The Gypsum Deposits of Nottingham and Derbyshire," Transactions of the Federated Institution, vol. xii. (1896), p. 107 J. G. Goodchild, "The Natural History of Gypsum," Proceedings of the Geologists' Association, vol. x. (1888), p. 425 George P. Merrill, "The Onyx Marbles," Report of the U. S. National Museum for 1893, p. 539.
Etymology
The English word "alabaster" was borrowed from Old French , in turn derived from Latin , and that from Greek () or (). The Greek words denoted a vase of alabaster.Alabastos, Henry George Liddell, Robert Scott, A Greek-English Lexicon, at Perseus
The name may be derived further from ancient Egyptian , which refers to vessels of the Egyptian goddess Bast. She was represented as a lioness and frequently depicted as such in figures placed atop these alabaster vessels."alabaster", Merriam-Webster Online Dictionary Ancient Roman authors Pliny the Elder and Ptolemy wrote that the stone used for ointment jars called alabastra came from a region of Egypt known as Alabastron or Alabastrites.
Properties and usability The purest alabaster is a snow-white material of fine uniform grain, but it often is associated with an oxide of iron, which produces brown clouding and veining in the stone. The coarser varieties of gypsum alabaster are converted by calcination into plaster of Paris, and are sometimes known as "plaster stone".
The softness of alabaster enables it to be carved readily into elaborate forms, but its solubility in water renders it unsuitable for outdoor work. If alabaster with a smooth, polished surface is washed with dishwashing liquid, it will become rough, dull and whiter, losing most of its translucency and lustre. The finer kinds of alabaster are employed largely as an ornamental stone, especially for ecclesiastical decoration and for the rails of staircases and halls. In contemporary applications, Egyptian calcite alabaster is still utilized by local artisans who employ traditional hand-carving methods. Due to its natural translucency, the stone is frequently shaped into decorative objects and lighting fixtures, such as lampshades and candle holders, allowing it to remain a relevant material in modern interior design.
Modern processing
Working techniques Alabaster is mined and then sold in blocks to alabaster workshops. There they are cut to the needed size ("squaring"), and then are processed in different techniques: turned on a lathe for round shapes, carved into three-dimensional sculptures, chiselled to produce low relief figures or decoration; and then given an elaborate finish that reveals its transparency, colour, and texture.
Marble imitation In order to diminish the translucency of the alabaster and to produce an opacity suggestive of true marble, the statues are immersed in a bath of water and heated gradually—nearly to the boiling point—in an operation requiring great care, because if the temperature is not regulated carefully, the stone acquires a dead-white, chalky appearance. The effect of heating appears to be a partial dehydration of the gypsum. If properly treated, it closely resembles true marble and is known as "marmo di Castellina".
Dyeing Alabaster is a porous stone and can be dyed into any colour or shade, a technique used for centuries. For this the stone needs to be fully immersed in various pigment solutions and heated to a specific temperature. The technique can be used to disguise alabaster. In this way an imitation of coral that is called "alabaster coral" is produced.
Types, occurrence, history
Typically only one type is sculpted in any particular cultural environment, but sometimes both have been worked to make similar pieces in the same place and time. This was the case with small flasks of the alabastron type made in Cyprus from the Bronze Age into the Classical period.Hermary, Antoine, Mertens, Joan R., The Cesnola Collection of Cypriot Art: Stone Sculpture, 2014, The Metropolitan Museum of Art, , 9781588395504, pp. 384-398
Window panels When cut into thin sheets, alabaster is translucent enough to be used for small windows. It was used for this purpose in Byzantine churches and later in medieval ones, especially in Italy. Large sheets of Aragonese gypsum alabaster are used extensively in the Cathedral of Our Lady of the Angels, dedicated in 2002 by the Los Angeles, California, Archdiocese. The cathedral incorporates special cooling to prevent the panes from overheating and turning opaque. The ancients used the calcite type, while the modern Los Angeles cathedral employs gypsum alabaster. There are also multiple examples of alabaster windows in ordinary village churches and monasteries in northern Spain.
Calcite alabaster
Calcite alabaster, harder than the gypsum variety, was used in ancient Egypt and the wider Middle East (except Assyrian palace reliefs), and also in modern times. It is found as either a stalagmitic deposit from the floor and walls of limestone caverns, or as a kind of travertine, similarly deposited in springs of calcareous water. Its deposition in successive layers gives rise to the banded appearance that the marble often shows on cross-section, from which its name is derived: onyx-marble or alabaster-onyx, or sometimes simply (and wrongly) as onyx. A defining physical characteristic of calcite alabaster is its light-diffusing capability. When carved to specific thicknesses, the stone scatters light evenly across its surface, preventing harsh shadows. This semi-translucent property makes it highly suitable for illuminated interior pieces.
Egypt and the Middle East Egyptian alabaster has been worked extensively near Suez and Assiut.
This stone variety is the "alabaster" of the ancient Egyptians and Bible and is often termed Oriental alabaster, since the early examples came from the Far East. The Greek name alabastrites is said to be derived from the town of Alabastron in Egypt, where the stone was quarried. The locality may owe its name to the mineral; though the origin of the mineral name is obscure
Ancient Roman historian Pliny the Elder, while writing about the origins of precious stones, discusses the Alabastrum stone (alabastrites). According to him, this stone derived from a distinct town Alabastrum, located near Upper Egypt's ancient capital Thebes.Pliny, Natural History, Book 37 Before that, Herodotus referred to myrrh alabastron (μύρου ἀλάβαστρον) containers for perfumes and oils.Histories (Herodotus) (Book 3, Chapter 20) The name of these containers, very widespread in Egypt and the ancient Mediterranean, was clearly linked with the name of the stone.C. H. Roosevelt 2008, Stone Alabastra in Western Anatolia. In New Approaches to Old Stones: Recent Studies of Ground Stone Artifacts, edited by Y. Rowan and J. Ebeling, 285–97. Approaches to Anthropological Archaeology Series. London: Equinox Publishing. - academia.edu
The "Oriental" alabaster was highly esteemed for making small perfume bottles or ointment vases called alabastra; the vessel name has been suggested as a possible source of the mineral name. In Egypt, craftsmen used alabaster for canopic jars and various other sacred and sepulchral objects. The sarcophagus of Seti I, found in his tomb near Thebes, is on display in Sir John Soane's Museum, London; it is carved in a single block of translucent calcite alabaster from Alabastron.
Algerian onyx-marble has been quarried largely in the province of Oran.
Calcite alabaster was quarried in ancient Israel in the cave known as the Twins Cave near Beit Shemesh. Herod used this alabaster for baths in his palaces.
North America In Mexico, there are famous deposits of a delicate green variety at La Pedrara, in the district of Tecali, near Puebla. Onyx-marble occurs also in the district of Tehuacán and at several localities in the US including California, Arizona, Utah, Colorado and Virginia.
Gypsum alabaster Gypsum alabaster is softer than calcite alabaster. It was used primarily in medieval Europe, and is also used in modern times.
Ancient and Classical Near East
"Mosul marble" is a kind of gypsum alabaster found in the north of modern Iraq, which was used for the Assyrian palace reliefs of the 9th to 7th centuries BC; these are the largest type of alabaster sculptures to have been regularly made. The relief is very low and the carving detailed, but large rooms were lined with continuous compositions on slabs around high. The Lion Hunt of Ashurbanipal and military Lachish reliefs, both 7th century BC and in the British Museum, are some of the best known.
Gypsum alabaster was widely used for small sculpture for indoor use in the ancient world, especially in ancient Egypt and Mesopotamia. Fine detail could be obtained in a material with an attractive finish without iron or steel tools. Alabaster was used for vessels dedicated for use in the cult of the deity Bast in the culture of the ancient Egyptians, and thousands of gypsum alabaster artifacts dating to the late 4th millennium BC also have been found in Tell Brak (modern Nagar), in Syria.
In Mesopotamia, gypsum alabaster was the material of choice for figures of deities and devotees in temples, as in a figure believed to represent the deity Abu dating to the first half of the 3rd millennium BC, which is kept in New York.
Aragon, Spain