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Slate was used by earlier cultures as whetstone to hone knives, [33] [34] but whetstones are nowadays more typically made of quartz. [35] In 18th- and 19th-century schools, slate was extensively used for blackboards and individual writing slates, for which slate or chalk pencils were used. [32] In modern homes slate is often used as table coasters.
The slate industry is the industry related to the extraction and processing of slate. Slate is either quarried from a slate quarry or reached by tunneling in a slate mine. Common uses for slate include as a roofing material, a flooring material, gravestones and memorial tablets, and electrical insulation.
The writing slate consisted of a piece of slate, typically either 4x6 inches or 7x10 inches, encased in a wooden frame. [1] Split slate was prepared by scraping with a steel edge, grinding with a flat stone and, finally, polishing with a mix of slate powder in water. Pencils were of a softer stone, such as shale, chalk or soapstone. [2]
The world's biggest consumer of slate is France, followed by the UK, USA and Germany. In 2012, Spain produced more than 580,000 tonnes (570,000 long tons; 640,000 short tons) of slate worth about $380 million. This made it the largest slate producer in the world, followed by China and Brazil. [3]
The use of blackboards changed methods of education and testing, as found in the Conic Sections Rebellion of 1830 in Yale. [18] Manufacturing of slate blackboards began by the 1840s. [4] Green porcelain enamel surface, was first used in 1930, and as this type of boards became popular, the word "chalkboard" appeared. [4]
Slate shingles are also called slate tiles, the usual name outside the US. Slate roof shingles are relatively expensive to install but can last 80 to 400 years depending on the quality of the slate used, and how well they are maintained. The material itself deteriorates only slowly, and may be recycled from one building to another.
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Slate is an online magazine that covers current affairs, politics, and culture in the United States. It was created in 1996 by former New Republic editor Michael ...