In 1839 the third source for rare earths became available. This is a mineral similar to gadolinite called uranotantalum (now called "samarskite") an oxide of a mixture of elements such as yttrium, ytterbium, iron, uranium, thorium, calcium, niobium, and tantalum. This mineral from Miass in the southern Ural Mountains was documented by Gustav Rose. The Russian chemist R. Harmann proposed that a new element he called "ilmenium" should be present in this mineral, but later, Christian Wilhelm Blomstrand, Galissard de Marignac, and Heinrich Rose found only tantalum and niobium (columbium) in it.
in 1839 the third source for rare earths became available this is a mineral similar to gadolinite called uranotantalum (now called "samarskite") an oxide of a mixture of elements such as yttrium ytterbium iron uranium thorium calcium niobium and tantalum this mineral from miass in the southern ural mountains was documented by gustav rose the russian chemist r harmann proposed that a new element he called "ilmenium" should be present in this mineral but later christian wilhelm blomstrand galissard de marignac and heinrich rose found only tantalum and niobium (columbium) in it