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Slate is a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low ...
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 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]
Slate is an example of a foliated metamorphic rock, originating from shale, and it typically shows well-developed cleavage that allows slate to be split into thin plates. [19] The type of foliation that develops depends on the metamorphic grade. [20]
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.
This method has been used since ancient times. In modern times, additional tests can be done. The trace will react in different ways to specific concentrations of nitric acid or aqua regia, thereby identifying the quality of the gold: 24 karat gold is not affected but 14 karat gold will show chemical activity.
About 1.6 million U.S. adults, or one-half of 1%, and 300,000 adolescents aged 13 to 17, or 1.4%, identify as transgender, according to a study by UCLA law school.
Virginia Slate This page was last edited on 5 October 2010, at 04:48 (UTC). Text is available under the Creative Commons Attribution-ShareAlike 4.0 ...