| xanthiosite | Ni3(AsO4)2 |
| xanthoconite | Ag3AsS3 |
| xanthophyllite | clintonite |
| xanthoxenite | Ca4Fe2(PO4)4(OH)2·3H2O |
| xenotime-(Y) | YPO4 |
| xiangjiangite | (Fe,Al)(UO2)4(PO4)2(SO4)2OH·22H2O |
| xifengite | Fe5Si3 |
| xilingolite | Pb3Bi2S6 |
| ximengite | BiPO4 |
| xingzhongite | (Pb,Cu,Fe)(Ir,Pt,Rh)2S4 |
| xitieshanite | FeSO4Cl·6H2O |
| xocomecatlite | Cu3TeO4(OH)4 |
| xonotlite | Ca6Si6O17(OH)2 |