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ASTM International has formulated and established a common definition for the technical aspect of the galling phenomenon in the ASTM G40 standard: "Galling is a form of surface damage arising between sliding solids, distinguished by microscopic, usually localized, roughening and creation of protrusions (e.g., lumps) above the original surface". [5]
Bristol Diamonds are quartz crystals found in geodes and geological rock formations which occur in dolomitic conglomerate in the Avon Gorge in Bristol, England.Their origin lies in geological processes of the Triassic period, about 250 to 200 million years ago.
Galling, a form of metal wear when two surfaces slide across one another; Bile, a fluid that aids in digestion; Colocynth, the bitter apple or vine of Sodom; Boldness or chutzpah, a personal characteristic of fearlessness and effrontery
George Ravenscroft (1632 – 7 June 1683) was an English businessman in the import/export and glass making trades. He is primarily known for his work in developing clear lead crystal glass (also known as flint glass ) in England .
British Plant Gall Society; A Field Guide to Plant Galls of the North East U.S. Archived 2020-11-12 at the Wayback Machine; To Be or Not To Be a Gall: The Story of Strange Growths on Plants Archived 2014-03-21 at the Wayback Machine; Insect Galls Archived 2020-11-09 at the Wayback Machine. Brandeis University "Common oak galls".
Bowl made from Derbyshire Blue John, on display in Castleton Visitor Centre French candelabra crafted of Blue John, c. 1860. Blue John (also known as Derbyshire Spar) is a semi-precious mineral, a rare form of fluorite with bands of a purple-blue or yellowish colour.
Dogtooth spar with fluorite from the Elmwood Mine in Tennessee. Spar is an old mining or mineralogy term used to refer to crystals that have readily discernible faces. A spar will easily break or cleave into rhomboidal, cubical, or laminated fragments with smooth shiny surfaces.
The Lothair Crystal (also known as the Lothar Crystal or the Susanna Crystal) is an engraved gem from Lotharingia in northwest Europe, showing scenes of the biblical story of Susanna, dating from 855–869. [1] The Lothair Crystal is an object in the collection of the British Museum.