Uranium ore for silver in the 16th century. F.E. Brückmann made the first mineralogical description of the mineral in 1727 and the vein deposit Jachymov in the Czech Republic became the type locality for uraninite. In 1789 the German chemist M. H. Klaproth discovered the element of uranium in a sample of pitchblende from the Johanngeorgenstadt vein deposit. The first industrial production of uranium was made from the Jachymov deposit and Marie and Pierre Curie used the tailings of the mine for their discovery of polonium and radium. Vein deposits consist of uranium minerals filling in cavities such as cracks, veins, fractures,
Uranium about 70% higher than that of lead, and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238 (99.2739–99.2752%), uranium-235 (0.7198–0.7202%), and a very small amount of uranium-234 (0.0050–0.0059%). Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years, making them useful in dating the age of the Earth. Many contemporary uses of