The samarium represents about 1 to 2% of the rare-earth that naturally occur in the earth crust. However, sometimes is possible to find ores where the samarium abundance reaches up to 7%.
The main ores with commercial interest for extraction of rare-earths are monazite and bastnasite, which contain about 2% of Sm2O3. Monazite is a rare-earth orthofosfate, and can be found in India, Sri-Lanka, Brazil, Australia, USA and South Africa. Bastnasite is a rare-earth fluorcarbonate, and occurs mainly in California.