Other minerals include apatite, magnetite, monazite and zircon. Beach sands include the minerals Ilmenite, rutile, zircon and monazite. The source of zircon, monazite, rutile, sometimes tungsten, and some ilmenite is usually granite. The phosphate is, in this case, contained within magmatic apatite, monazite, or other rare-earth phosphates. Dysprosium is obtained primarily from monazite sand, a mixture of various phosphates. An electron microprobe is usually used for the measurement of monazite composition. Thorium occurs in several minerals including thorite (ThSiO), thorianite (ThO + UO) and monazite. Rare earths are found in various minerals such as monazite and bastnasite. It is most often recovered commercially from monazite sand (0.03% ytterbium). However, thulium also occurs in the minerals monazite, xenotime, and euxenite. The following steps detail the extraction of rare-earth metals from monazite ore. Monazite sand deposits are inevitably of the monazite-(Ce) composition. India, Madagascar, and South Africa have large deposits of monazite sands. This results in fluid inclusions in monazite. Subsequent investigations found the source of the radiation was natural, originating from monazite deposits.