A volcanic mineral that was the first form of natural glass used by humans. It is usually black, but it can also be very dark red or green; its splinters are often transparent or translucent.
(from Greek, “wine pourer”) A pitcher with a trefoil mouth, used in ancient Greece to transfer wine from the mixing bowl to the cup. Between the sixth and third centuries B.C., miniature core-formed oenochoes were used as perfume bottles.
Glassware shaped solely by inflation with a blowpipe and manipulation with tools.
(perhaps from Arabic qumqum, “sprinkler”) A sprinkler with a tall, narrow neck and an oblate spheroid body. Omoms were used in the Islamic world for sprinkling perfume.
(from Greek omphalos, “navel”) A bowl with a hollow, raised boss (the “navel”) at the center.
Glass that resembles an opal, being translucent and white, with a grayish or bluish tinge.
(1) A type of late 19th-century Art Glass, made by covering a gather of colored glass with a layer of colorless glass containing bone ash and arsenic or the mineral cryolite from Greenland. The parison was inflated in a mold to produce raised decoration. When the parison was reheated, the raised areas became opalescent. (2) A type of glass resembling the iridescent gemstone opal, which was developed by Frederick Carder (1863-1963) at Steuben Glass Works in Corning, New York.
Work that is perforated. Openwork in glass objects can be made by creating a network of trails, by casting (see Diatreta), or by cutting (see Cage cup).
A cylindrical or truncated conical one-piece mold with a patterned interior. The mold is open at the top so that a parison can be dipped into it and then inflated. It is also known as an optic mold.
Glass of extreme purity and with welldefined optical properties, which was originally created for making lenses and prisms.
(from Latin, “cut work”) Decoration on a wall or floor, made by fitting together flat elements of different shapes and colors. The ancient Romans sometimes used glass to make opus sectile ornament.
(from French, “ground gold”) An alloy with a copper base, used for decoration. Some glass objects have ormolu mounts.
A by-product of mold blowing, this is the portion of the parison that remains outside the mold. The overblow, or moil, is usually removed by cracking off.
A layer of glass that covers a layer of a different color, often as the result of casing or flashing.