Alabaster

Alabaster is a general term applied to two types of fine-grained stone, white or off-white in colour, usually with a translucent appearance through which light passes slightly. Stone of this kind is used for statues, vessels, decorative inlays and ornamental building work, as it can be worked easily with hand tools.

Two chemically distinct types share the name alabaster: gypsum (calcium sulfate with water), which is soft; and calcite (calcium carbonate), which is harder and sometimes called 'Egyptian alabaster' or 'onyx marble'. Both are softer than true marble, which is why artists have preferred them.

Physical Properties

Gypsum alabaster is very soft: fingernails can scratch it. For this reason it wears and ages readily, and is recommended for interior use rather than exterior exposure, as rain can damage it. Calcite alabaster is harder, though fine abrasives can affect it. Both transmit light slightly when made thin, which was exploited in lamps and window panels in ancient churches.

Historical Use

Early Egypt saw calcite alabaster made into solid vessels and storage jars, as well as canopic jars for holding mummified organs. The Middle East and Mesopotamia produced alabaster statues and decorative vessels. In medieval Europe and during the Renaissance, gypsum alabaster was fashioned into church ornaments, embellished sarcophagi and decorative carvings.

Quarrying and Craft

Alabaster is extracted from quarries and mines. After roughing out, it is shaped using chisels, files and rotary tools, then finished with fine abrasive paper. To achieve a polished surface, waxes and oils are sometimes applied. Colour can be enhanced by heating or staining with mineral dyes.