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Abrade = to wear down orrub away; to scrape or wear away by friction or erosion. Abrasion is one of the main ways that stone is shaped. From Latin abradere toscrape off, from ab- off, from + radere to scrape Arelated word is to grind which canmean to wear down, pulverise or crush by friction, often between two firmsurfaces. You might grind wheat into flour but you would not abrade it.
Abrasive = a substance that wears down a surface by rubbing againstit. Abrasives are available in many forms, including powders, compounds,papers, wheels or disks, brushes. Sand has been used in many forms as anabrasive, sometimes to erode or shape, sometimes to smooth a rough surface,sometimes to cut. Examples of some abrasives are pumice, emery, corundum, andcarborundum.
Acrolith = a sculpture combining parts in stone with parts in anothermaterial. Perhaps the head and hands, sometimes feet, are of marble and therest of the figure is made of wood, clay or less expensive stone. Ancient Greekacroliths may be ancestors of porcelain dolls common in the 19thcentury where head and hands are ceramic and the bodies are of cloth.
Adamant = legendary unbreakable stone, usedfiguratively today to mean something very strong. At one point it was the wordfor diamond. Homer uses it as a personal epithet. By confusion with the Latin adamare, to have an attraction for, itsometimes was used to refer to the lodestone.
Adit = horizontal entrance to an underground mine, such as from the side of acliff. Sometimes called 'day drift,' 'day hole,' or 'watergate.' The last term because most seams were cut onsuch a level that the adit would drain the water from the working shaft.
Aeolian (or Eolian or Æolian) = the activity of the winds in particular the ability ofwind to shape the surface of the Earth. Winds are one of the forces that erode,transport, and deposit materials, especially effective in open spaces wherethere is sparse vegetation and enough loose sediments too effectively act assandblast.
Althoughwater (or sand in water) is a more powerful eroding force than wind, Aeolianprocesses are important in arid environments such as deserts. Aeroliths are desert stones carved bythe wind. The word comes from theGreek god, Æolus, the keeper of the winds.
Aeroliths=stones carved by the wind.
Agassiz = Jean Louis Rudolphe Agassiz a Swiss naturalist, geologist andrenowned teacher. In 1833 published a comprehensive guide to fossil fish and in1836 an important study of glaciers. Agassiz was initially drawn to glaciers byan interest in erratic stones and it was Agassiz who first introduced the ideaof earlier ice ages. He taught at Harvard from 1848, where he trainedgenerations in the power of observation. Among his favourite expressions were: "If you study nature in books, when you goout-of-doors you cannot find her." "It's not text books we want, but students. The book of nature is alwaysopen." and "Strive to interpret whatreally exists." He is buriedin Mt Auburn cemetery in Cambridge, Massachusetts, and by his grave stands aboulder from the moraine from Lauteraar, in the Bernese Alps.
Agglomerate = A volcanic rock consisting of roundedand angular fragments fused together.
Etymology: Latin agglomeratus, pastparticiple of agglomerare to heap up, join, from ad- + glomer-,glomus ball
Agglomerates (from the Latin 'agglomerare' meaning 'to form into a ball') are coarseaccumulations of large blocks of volcanic material that contain at least 75% bombs.
Agglomerates are typically found near volcanic vents and within volcanic conduits, where they may be associated with pyroclastic or intrusive volcanic breccias.
Agrape = perhaps a metal clamp.
Aiguille = a sharp-pointed pinnacle of rock a peak or a rock shaped like a needle;also: an instrument for drilling holes in rock or masonry.
Alkahest = Alkahest (oralcahest) is a hypothetical universal solvent, having the power to dissolveevery other substance, including gold. It was much sought after by alchemistsfor what they thought would be its invaluable medicinal qualities. The name isbelieved to have been invented by Philippus Aureolus Paracelsus (1493–1541)from Switzerland, who modelled it on similar words taken from Arabic, such as'alkali'. He believed that thiselement alkahest was, in fact, the philosopher's stone. A potential probleminvolving alkahest is that, if it dissolves everything, then it cannot beplaced into a container, because it would dissolve the container.
Alignment = a more or less straight row of standing stones.
Alvar = isa specificbiological environment on a limestone plain where there is thin soil or none atall. The use of the word "alvar" comes from Scandinavia where itoriginally referred to a large area on the Swedish island of Öland. The wordhas been adapted to refer to similar places worldwide. Alvar soil, usually lessthan 2.0 centimeters thick, and is sometimes so thin that limestone slabs areactually exposed. [Also see Karst]
Amygdule = (oramygdales) form when the gas bubbles in extrusive igneous rocks are in filledwith a secondary mineral such as calcite, quartz, chlorite or one of thezeolites. Amygules usually form after the rock has hardened into its place, andtherefore associated with low-temperature changes. Amygules may often beconcentrically zoned.
The wordis derived from the Latin (amygdala) and Greek (αμυγδαλ?) words for almond,reflecting a typical shape of an in filled vesicle.
Amorphous = without shape, which means no long-rangeorder in the position of the atoms. The opposite of a crystalline shape. Instone this usually means that the stone cooled too quickly for a crystallinestate to develop.
Anaglyph = see glytics [Greekana – ' up, upward; back,backward, against; again, anew" + gluphein -"to carve"] Sometimes anaglyphrefers to low relief carving, sometimes to the superimposition of two images toencode a sense of the three dimensional.
Anorthosite = is an igneous rock formed deep underground in dikes and intrusions,forming almost 60% of the earths crust.
Aragonite = is one of the two common,naturally occurring crystal forms of calcium carbonate (the other form is themineral calcite.) Aragonite can be formed by both biological and physicalprocesses. Aragonite forms naturally in almost all mollusk shells, and as thecalcareous endoskeleton of warm- and cold-water corals. In mollusk shells some crystal forms, beingbiologically controlled, are distinctively different from those of inorganicaragonite. In some mollusks, the entire shell is aragonite; in others,aragonite forms only parts of a shell (with calcite). Aragonite also forms asinorganic precipitate in the oceans called marine cements. If Aragonite forms infreshwater caves it is referred to as speleothems.
Artesianaquifer = is aconfined pressurised aquifer containing groundwater that will flow upwardthrough a well, called an artesian well, without the need for pumping. Watermay even reach the ground surface if the natural pressure is high enough.
An aquifer is a layer of soft rock, likelimestone or sandstone that absorbs water from an inlet path. Porous stone isconfined between impermeable rocks or clay. This keeps the pressure high, sowhen the water finds an outlet, it overcomes gravity and goes up instead ofdown. The recharging of aquifers happens when the water table at its rechargezone is at a higher elevation than the head of the well.
Fossilwater aquifers can also be artesian if they are under sufficient pressure fromthe surrounding rocks. This is similar to how many newly tapped oil wells arepressurised.
The "Great Artesian Basin" in central Australiais the largest and artesianbasin in the world, covering a total of 1,711,000 square kilometres (661,000 sqmiles). It underlies 23% of thecontinent The basin is 3,000 metres (9,800 ft) deep in places and is estimatedto contain 64,900 cubic kilometres of water.
Ashlar = also called 'dressed' stone isa rectangular block of stone with square edges and even faces. Ashlar blocks used to be usedextensively in the construction of buildings used as brick. The external faceof an ashlar might be smooth or polished, or 'decorated' by small marks or groovesmade by the mason's chisel or lines from an abrasive tool called a 'mason's drag.'
Attrition = physical wear, loss.
Augite = one of thealuminous varieties of the mineral pyroxene, consisting chiefly of silica,magnesia, iron, and lime; it has a greenish, brownish, or pure black colour,and occurs mostly in volcanic rocks. Perhaps an inferior variety of turquoise
(Formerly taken in a wider sense assynonymous with pyroxene; while "the Augite of Werner included only the blackmineral of igneous rocks—the volcanic schorl of earlier authors" Dana.).
Avenue = in reference to prehistoric sites and monoliths, twoparallel rows of standing stones or a grand ceremonial way bordered by ditchesand banks of earth generally leading to a ceremonial centre such as atStonehenge.
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