thorium
Thorium is an element with atomic number 90 and element symbol is Th. One of actinoid elements, silver-white metal. In 1828, it was discovered by Tol Stone by Jens Bergerius of Sweden and named after the thunder god Thor of the Northern European myth which is the origin of its name. It is contained a lot in monazite sand, and it reaches 10% in many things. Monazite sand is a rare earth element (cerium, lanthanum, neodymium) resource and it is obtained as a byproduct thereof. The main producing regions are Australia, India, Brazil, Malaysia, Thailand. The naturally occurring isotope is only one kind of radioactive thorium 232, and there is no stable isotope. However, its half-life is very long, 1.405 billion years, and it exists considerably abundantly in the crust (around 10 ppm). It is less soluble in water and less in seawater. ...