Editing Coffinite (section)

==Crystal structure==
Coffinite is [[isostructural]] with the orthosilicates zircon (ZrSiO<sub>4</sub>) and thorite (ThSiO<sub>4</sub>).<ref>{{cite journal | last1 = Pointeau | first1 = V. |display-authors=et al | year = 2009 | title = Synthesis and Characterization of Coffinite | journal = Journal of Nuclear Materials | volume = 393 | issue = 3 | pages = 449–458 | doi=10.1016/j.jnucmat.2009.06.030| bibcode = 2009JNuM..393..449P }}</ref>  Stieff et al. analyzed coffinite using the x-ray powder diffraction technique and determined that it has a tetragonal structure.<ref name=Stieff56/>  Occurring naturally with U<sup>4+</sup> cations, the UO<sub>8</sub> triangular dodecahedra coordinate with edge-sharing, alternating SiO<sub>4</sub> [[tetrahedra]] in chains along the c-axis.<ref name=Zhang09/>  The central uranium site of coffinite is surrounded by eight SiO<sub>4</sub> tetrahedra.  The lattice dimensions of naturally-occurring and synthetic coffinite are similar, with a naturally-occurring sample from Arrowhead Mine, Mesa County, Colorado having a=6.93kx, c=6.30kx, and a sample synthesized by Hoekstra and Fuchs having a=6.977kx and c=6.307kx.<ref name=":0" /><ref name=Hoekstra56/>