Ytterbium is one of the less abundant rare-earths. This element is slightly less abundant than boron, molybdenum and thallium, but slightly more abundant than antimony and tantalum. The main ores that contain ytterbium are euxenite, gadolinite, monazite and xenotime. Euxenite is a complex titanium-niobium tantalic that contains small amounts of thorium and uranium. The main deposits of this mineral can be found in Idaho. Gadolinite contains a beryllium and iron silicate, and occurs mainly in Scandinavia. Monazite is a complex phosphate that contains thorium and vestiges other rare earths. This mineral is the most important source of the element. The most important deposits are located in Florida, Idaho and also in Australia, Brazil, India and South Africa. Smaller deposits occur in Egypt, Malawi, Sri Lanka, Indonesia, Malaysia, Korea, Uruguay and Argentina. Xenotime is a rare earth that occurs associated to monazite, although in small amounts.