ABSTRACT
Most common in placers. It consists of chains of alternating BO4 tetrahedra and AO9 polyhedra. The monoclinic monazite structure does not permit open tunnels, and is approximately 10% denser than zircon structure. Monazite resists metamictization despite being exposed to high alpha-decay arising from its high radioactive content (upto 27 wt% of UO2 + ThO2). Also, monazite is highly resistant to dissolution, with irradiated, fully amorphous synthetic monazite being as resistant as crystalline zircon.
