Decay chain equilibrium is achieved, each successive daughter isotope is present in direct proportion to its half-life; but since its activity is inversely proportional to its half-life, each nuclide in the decay chain finally contributes as many individual transformations as the head of the chain, though not the same energy. For example, uranium-238 is weakly radioactive, but pitchblende, a uranium ore, is 13 times more radioactive than the pure uranium metal because of the radium and other daughter isotopes it contains. Not only are unstable radium isotopes significant radioactivity emitters, but as the next stage in the decay chain they also generate
Uraninite Uraninite Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO, but due to oxidation the mineral typically contains variable proportions of UO. Additionally, due to radioactive decay, the ore also contains oxides of lead and trace amounts of helium. It may also contain thorium and rare earth elements. Uraninite used to be known as pitchblende (from "pitch", because of its black color, and "blende", a term (otherwise meaning "shade" or "screen") used by German miners to denote minerals whose density suggested metal content, but whose exploitation, at the time they were