Alabaster Calcite Alabaster Gypsum Alabaster See Also

Alabaster (sometimes called satin spar) is a name applied to varieties of two distinct minerals: gypsum (a hydrous sulfate of calcium) and the calcite (a carbonate of calcium). The former is the alabaster of the present day; the latter is generally the alabaster of the ancients.

The two kinds are readily distinguished from each other by their relative hardnesses. The gypsum kind is so soft as to be readily scratched by a finger-nail ( hardness 1.5 to 2), while the calcite kind is too hard to be scratched in this way (hardness 3), though it does yield readily to a knife. Moreover, the calcite alabaster, being a carbonate, effervesces on being touched with hydrochloric acid, whereas the gypsum alabaster, when so treated, remains practically unaffected.

1 Calcite Alabaster

This substance, the "alabaster" of scripture, 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, but the locality probably owed its name to the mineral; the origin of the mineral-name is obscure, and it has been suggested that it may have had an Arabic origin. This "Oriental" alabaster was highly esteemed for making small perfume-bottles or ointment vases called alabastra, and this has been conjectured to be a possible source of the name. Alabaster was also employed in Egypt for Canopic jars and various other sacred and sepulchral objects. A splendid sarcophagusA sarcophagus is a stone container for a coffin or body. The word comes from Greek sarkophagos sigma;αρκοφαγο&sigmaf , which means "eater of flesh". Herodotus believed, erroneously, that sarcophagi (the Lati, sculptured in a single block of translucent calcite alabaster from Alabastron, is in the Soane MuseumThe Soane Museum is a museum of architecture, and was formerly the house and studio of Sir John Soane. It holds many drawings and models of his projects and the collections of paintings, drawings and antiquities that he assembled. The Museum is located in, LondonLondon is the capital of the United Kingdom and of England, and with over seven million inhabitants in the Greater London area, is the second-most populous conurbation in Europe (after Moscow). From being Londinium the capital of the Roman province of Bri. This was discovered by Giovanni Belzoni in 1817Events March 4 James Monroe succeeds James Madison as the President of the United States of America April Earthquake in Palermo, Italy April 3 Princess Caraboo appears in Almondsbury in Gloucestershire, England July 4 At Rome, New York, construction on th in the tomb of Seti ISeti I was a pharaoh of Ancient Egypt (19th dynasty), the son of Rameses I and Queen Sitre and later the father of Rameses II. According to some historians he reigned between 1291 BC and 1278 BC, according to others between 1328 BC and 1298 BC or between near ThebesFor the ancient capital of Boeotia, see Thebes, Greece. Thebes (also known as Niut Ammon was the capital of Egypt during the period of the Middle and New Kingdoms. Located on the banks of the Nile — with temples, palaces, and the city of the living on the. It was purchased by Sir John SoaneSir John Soane ( 10 September 1753 20 January 1837) was a British architect who specialised in the Neo-Classical tradition. He was born at Goring-On-Thames near Reading, the son of a bricklayer. He trained as an architect, first under George Dance the You, having previously been offered to the British MuseumThe British Museum is one of the world's greatest and most famous museums. It was established in 1753 by Sir Hans Sloane, a physician and scientist who collected lots of literature and art, on its present site at Montague House in London, United Kingdom,.

When cut in thin sheets, alabaster is translucent enough to be used for small windows, and has been used so in medieval churches, especially in Italy.

Calcite alabaster is either a stalagmitic deposit, from the floor and walls of limestone caverns, or 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, whence it is known as onyx-marble or alabaster-onyx, or sometimes simply as onyx -- a term which should, however, be restricted to siliceous minerals. Egyptian alabaster has been extensively worked near Suez and near Assiut; there are many ancient quarries in the hills overlooking the plain of Tell el Amarna. The

2 Gypsum Alabaster

In the present day, when the term "alabaster" is used without any qualification, it invariably means a fine-grained variety of gypsum. This mineral, or alabaster proper, occurs in England in the Keuper marls of the Midlands, especially at Chellaston in

Derbyshire, at Fauld in Staffordshire and near Newark in Nottinghamshire. At all these localities it has been extensively worked. It is also found, though in subordinate quantity, at Watchet in Somerset, near Penarth in Glamorganshire, and elsewhere. In Cumbria it occurs largely in the New Red rocks, but at a lower geological horizon. The alabaster of Nottinghamshire and Derbyshire is found in

thick nodular beds or "floors" in spheroidal masses known as "balls" or "bowls," and in smaller lenticular masses termed "cakes." At Chellaston, where the alabaster is known as "Patrick," it has been worked into ornaments under the name of "Derbyshire spar" -- a term more properly applied to fluorspar.

The finer kinds of alabaster are largely employed as an ornamental stone, especially for ecclesiastical decoration and for the rails of staircases and halls. Its softness enables it to be readily carved into elaborate forms, but its solubility in water renders it inapplicable to outdoor work. The purest alabaster is a snow-white material of fine tiniforni grain, but it is often associated with an oxide of iron, which produces brown clouding and veining in the stone. The coarser varieties of alabaster are converted by calcination into plaster of Paris, whence they are sometimes known as "plaster stone."

On the continent of Europe, the centre of the alabaster trade is Florence, Italy. Tuscan alabaster occurs in nodular masses embedded in limestone, interstratified with marls of Miocene and Pliocene age. The mineral is largely worked by means of underground galleries,in the district of Volterra. Several varieties are recognized -- veined, spotted, clouded, agatiform, and others. The finest kind, obtained principally from Castellina , is sent to Florence for figure-sculpture, while the common kinds are carved at a very cheap rate locally into vases, clock-cases and various ornamental objects, in which a large trade is carried on, especially in Florence, Pisa and Leghorn.

In order to diminish the translucenc y of the alabaster and to produce an opacity suggestive of true marble, the statues are immersed in a bath of water and gradually heated nearly to the boiling-point -- an operation requiring great care, for if the temperature is not carefully regulated, 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 very closely resembles true marble and is known as marmo di Castellina . It should be noted that sulphate of lime (gypsum) was used also by the ancients, and was employed, for instance, in Assyrian sculpture, so that some of the ancient alabaster is identical with the modern stone.

Alabaster may be stained by digesting it, after heing heated in various pigmentary solutions. In this way a good imitation of coral has been produced (alabaster coral).

Black Alabaster is a rare form of the gypsum-based mineral found in only three veins in the world, one each in Oklahoma (USA), Italy and China.

Alabaster Caverns State Park, near Freedom, Oklahoma is home to a natural gypsum cave in which much of the gypsum is in the form of alabaster. There are several types of alabaster found at the site, including pink, white, and the rare black alabaster.

1 See also

list of minerals

Alabaster is also a city in Alabama. See: Alabaster, Alabama
Alabaster is also a township in Michigan. See: Alabaster Township, Michigan

This article incorporates text from the public domain 1911 Encyclopædia Britannica. 1911 Britannica

Minerals

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1 Calcite Alabaster

2 Gypsum Alabaster

1 See also

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