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,
Transactinide element atomic number greater than uranium (92). The transactinide elements all have electrons in the 6d subshell in their ground state. Except for rutherfordium and dubnium, even the longest-lasting isotopes of transactinide elements have extremely short half-lives, measured in seconds, or smaller units. The element naming controversy involved the first five or six transactinide elements. These elements thus used systematic names for many years after their discovery had been confirmed. (Usually the systematic names are replaced with permanent names proposed by the discoverers relatively shortly after a discovery has been confirmed.) Transactinides are radioactive and have only been obtained synthetically in