Agate

Agate /ˈæɡət/ is a cryptocrystalline variety of silica, chiefly chalcedony, characterised by its fineness of grain and brightness of color. Although agates may be found in various kinds of rock, they are classically associated with volcanic rocks and can be common in certain metamorphic rocks.

Etymology and history

The stone was given its name by Theophrastus, a Greek philosopher and naturalist, who discovered the stone along the shore line of the river Achates (Greek: Ἀχάτης) in present-day Sicily, sometime between the 4th and 3rd centuries BC. Colorful agates and other chalcedonies were obtained over 3,000 years ago from the Achates River, now called Dirillo.

Ancient use

Agate is one of the most common materials used in the art of hardstone carving, and has been recovered at a number of ancient sites, indicating its widespread use in the ancient world; for example, archaeological recovery at the Knossos site on Crete illustrates its role in Bronze Age Minoan culture.

Formation and characteristics

Agate (typography)

An agate (US) or ruby (UK) is a unit of typographical measure. It is 5.5 typographical points, or about 1/14 of an inch. It can refer to either the height of a line of type or to a font that is 5.5 points. An agate font is commonly used to display statistical data or legal notices in newspapers. It is considered to be the smallest point size that can be printed on newsprint and remain legible.

Due to the small size of agate compared to typical newspaper body text that might be 8 to 10 points and due to its use for statistical, stock, racing or other table uses, the term "agate" may also refer to tables and texts using this point size. The general description "agate" refers to the collection of miscellaneous tables, stock tables, horse racing and sports tables and so forth that may be in a newspaper.

From the American Dictionary of Printing and Bookmaking (1894):

See also

References

Agate (rocket)

Agate is the designation of an unguided French test rocket. The Agate has a length of 8.50 metres, a diameter of 0.80 metres, a start mass of 3.2 tonnes, a takeoff thrust of 186 kN and a ceiling of 20 km. The Agate was launched from the Hammaguir and Ile de Levant test sites, in order to test instrument capsules and recovery systems.

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