A lustrous gray metalloid , it is found in nature mainly as the sulfide mineral stibnite Sb 2 S 3. Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name kohl. The earliest known description of the metal in the West was written in by Vannoccio Biringuccio. For some time, China has been the largest producer of antimony and its compounds, with most production coming from the Xikuangshan Mine in Hunan. The industrial methods for refining antimony are roasting and reduction with carbon or direct reduction of stibnite with iron. The largest applications for metallic antimony are an alloy with lead and tin and the lead antimony plates in lead—acid batteries.
Dubious Radiogenic Pb Places U-Th-Pb Mineral Dating in Doubt
About Uranium-Lead Dating
The discovery of the chemical elements known to exist as of is presented in chronological order. The elements are listed generally in the order in which each was first defined as the pure element, as the exact date of discovery of most elements cannot be accurately determined. There are plans to synthesize more elements, and it is not known how many elements are possible. Each element's name , atomic number , year of first report, name of the discoverer, and notes related to the discovery are listed. From Wikipedia, the free encyclopedia.
Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes , such as strontium 90 Sr and technetium 99 Tc , are only found on Earth as a result of human activity, and some, like potassium 40 K , are only present due to natural processes, a few isotopes, e. The concentration and location of some natural isotopes, particularly uranium U , can be affected by human activity. Radioactivity is present everywhere , and has been since the formation of the earth. Natural radioactivity detected in soil is predominantly due to the following four natural radioisotopes: 40 K, Ra, U, and Th.
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