U thhe dating of phosphates apatite monazite and xenotime
Craig, Oxygen isotope evidence against bulk recycled sediment in the mantle sources of Pitcairn Island lavas, Nature, 377 (1995) 138-141.
Neroda, Noble gases in the Earth’s mantle, Annual Reviews Earth Planet.
Kass Modeling of the temperature sensitivity of the apatite (U-Th)/He thermochronometer , Chem.
Norman, He as a tracer of continental dust - a two million year record of eolian flux to the equatorial western Pacific, Geochim.
It crystallizes in the tetragonal system, forming pyramidal or prismatic crystals; it is isostructural with zircon. It has a hardness of 4–5 on the mineralogical scale and a density of 4,450-4,590 kg/ m.
It occurs in granites and pegmatites in the form of granules or crystals ingrown into feldspar or quartz; it also occurs in alluvial deposits.
These examples are from the Cambridge English Corpus and from sources on the web.