semi-precious stone featuring bands of different colors
of quartz; Cameo stone; Jet black; Banded chalcedony; Intaglio
stone; Stone used for chess sets
once a year
in English language:
39901 / 86800
is a cryptocrystalline form of quartz. The colors of its bands
range from white to almost every color (save some shades, such as
purple or blue.) Commonly, specimens of onyx available contain
bands of colors of white, tan, and brown. Sardonyx is a variant
in which the colored bands are sard (shades of red) rather than
black. Pure black Onyx is common, and perhaps the most famous
variety, but not as common as Onyx with banded colors.
agate-like sardonyx (banded agate). The specimen is 2.5 cm (1
inch) wide.It is usually cut as a cabochon, or into beads, and is
also used for intaglios and cameos, where the bands make the
image contrast with the ground. Some onyx is natural but much is
produced by the staining of agate.
name has sometimes been used, incorrectly, to label other banded
lapidary materials, such as banded calcite found in Mexico,
Pakistan, and other places, and often carved, polished and sold.
This material is much softer than true onyx, and much more
readily available. The majority of carved items sold as 'Onyx'
today are this carbonate material.
article is licensed under the GNU
Free Documentation License.
It uses material from the Wikipedia