Trace amounts of francium have been found in uranium and thorium mineral ores. In these ores, the francium element is present in an isotope form, number 223. Isolation has so far proved unsuccessful as any element that is formed immediately decays again; it has a half life of only 22 minutes. Francium has been successfully synthesized, but this too is an extremely complicated procedure and only very minute amounts can be synthesized. A nuclear reaction involving an isotope of gold and oxygen will produce francium isotopes; the isotopes are then isolated using a magneto-optic trap. Radium bombardment with neutrons and thorium protons can also synthesize francium. Francium that has been created has been held as an ultra-cold gas; in this state the atoms of the element were close to absolute zero. The very tiny amounts of francium that have been synthesized have been so small that no measurements of the weight could be obtained.