Marbles are used principally for buildings and monuments, interior decoration, statuary, table tops, and novelties. Colour and appearance are their most important qualities. Resistance to abrasion, which is a function of cohesion between grains as well as the hardness of the component minerals, is important for floor and stair treads. The ability to transmit light is important for statuary marble,…
Asbestos Asbestos, any of several minerals that readily separate into long, flexible fibres. Chrysotile, the fibrous form of the mineral serpentine, is the best-known type and accounts for about 95 percent of all asbestos in commercial use. It is a hydrous magnesium silicate with the chemical composition of Mg3Si2O5(OH)4. The other types all belong to the amphibole group of minerals and include…
Origins of agriculture, the active production of useful plants or animals in ecosystems that have been created by people. Agriculture has often been conceptualized narrowly, in terms of specific combinations of activities and organisms—wet-rice production in Asia, wheat farming in Europe, cattle ranching in the Americas, and the like—but a more holistic perspective holds that humans are environmental engineers who disrupt terrestrial habitats in specific ways. Anthropogenic disruptions such as clearing…
Igloo, also spelled iglu, also called aputiak, temporary winter home or hunting-ground dwelling of Canadian and Greenland Inuit (Eskimos). The term igloo, or iglu, from Eskimo igdlu (“house”), is related to Iglulik, a town, and Iglulirmiut, an Inuit people, both on an island of the same name. The igloo, usually made from blocks of snow and dome-shaped, is used only in the area…
Masonry Masonry, the art and craft of building and fabricating in stone, clay, brick, or concrete block. Construction of poured concrete, reinforced or unreinforced, is often also considered masonry. masonry The art of masonry originated when early man sought to supplement his valuable but rare natural caves with artificial caves made from piles of stone. Circular stone huts, partially…
Climate, conditions of the atmosphere at a particular location over a long period of time; it is the long-term summation of the atmospheric elements (and their variations) that, over short time periods, constitute weather. These elements are solar radiation, temperature, humidity, precipitation (type, frequency, and amount), atmospheric pressure, and wind (speed and direction). From the ancient Greek origins of the word (klíma, “an inclination or slope”—e.g., of…
Industry, a group of productive enterprises or organizations that produce or supply goods, services, or sources of income. In economics, industries are customarily classified as primary, secondary, and tertiary; secondary industries are further classified as heavy and light. Primary Industry This sector of a nation’s economy includes agriculture, forestry, fishing, mining, quarrying, and the extraction…
Construction, also called building construction, the techniques and industry involved in the assembly and erection of structures, primarily those used to provide shelter. Construction is an ancient human activity. It began with the purely functional need for a controlled environment to moderate the effects of climate. Constructed shelters were one means by which human beings were able to adapt themselves to a wide…