Naturally Occurring Isotopes
There are only 2 known naturally occurring isotopes of lanthanum:
| Isotopes | Mass | Natural Abundance |
|
138Lanthanum |
137.907112 | 99.91% |
|
139Lanthanum |
138.9063533 | 0.09% |
Where It's Found and How It's Obtained
Most commercial grade lanthanum is found in, and obtained from, a type of sand called monazite sand. This is a mixture of most of the rare-earth metals and some other elements (calcium, thorium, and cerium). Often, this sand is weighed to be about 50% rare-earth metals and roughly 25% lanthanum. All the other metals are removed by either flotation processes or magnetically; however, the process of separating the rare-earths from each other proves difficult. This is done by a method called ion-exchange displacement. This process often results in a lanthanum ion that can react with chloride and fluoride to form compounds.