Beginning with U.
- UakititeVNMineralnative
- UchucchacuaiteAgMnPb3Sb5S12Mineralsulfide
- UdinaiteNaMg4(VO4)3Mineralphosphate
- UdumineliteCa3Al8(PO4)2O12·2H2OMineralphosphate
- Uedaite-(Ce)Mn2+CeAl2Fe2+(Si2O7)(SiO4)O(OH)Mineralsilicate
- UklonskoviteNaMg(SO4)F · 2H2OMineralsulfate
- UlexiteNaCaB5O6(OH)6 · 5H2OMineral—
- Ulfanderssonite-(Ce)(Ce15Ca)E16Mg2(SiO4)10(SiO3OH)(OH,F)5Cl3Mineralsilicate
- UllmanniteNiSbSMineralsulfide
- UlrichiteCaCu(UO2)(PO4)2 · 4H2OMineralphosphate
- UlvöspinelFe2+2TiO4Mineraloxide
- UmangiteCu3Se2Mineralsulfide
- UmbaliteMg3Al2(SiO4)3 - Mn3Al2(SiO4)3Variety—
- UmbiteK2ZrSi3O9 · H2OMineralsilicate
- UmbozeriteNa3Sr4ThSi8(O,OH)24Mineralsilicate
- UmbrianiteK7Na2Ca2[Al3Si10O29]F2Cl2Mineralsilicate
- Umohoite(UO2)(MoO4) · 2H2OMineraloxide
- UngavaitePd4Sb3Mineralsulfide
- UngemachiteK3Na8Fe3+(SO4)6(NO3)2 · 6H2OMineralsulfate
- UpaliteAl(UO2)3(PO4)2O(OH) · 7H2OMineralphosphate
- UralboriteCaB2O2(OH)4Mineral—
- UraloliteCa2Be4(PO4)3(OH)3 · 5H2OMineralphosphate
- Uramarsite(NH4)(UO2)(AsO4) · 3H2OMineralphosphate
- Uramphite(NH4)(UO2)(PO4) · 3H2OMineralphosphate
- UrancalcariteCa(UO2)3(CO3)(OH)6 · 3H2OMineralcarbonate
- UraniniteUO2Mineraloxide
- Uranium-bearing ZirconZr(SiO4)Variety—
- UranocirciteBa(UO2)2(PO4)2 · 10H2OMineralphosphate
- Uranoclite(UO2)2(OH)2Cl2(H2O)4Mineralhalide
- UranophaneCa(UO2)2(SiO3OH)2 · 5H2OMineralsilicate
- Uranopilite(UO2)6(SO4)O2(OH)6 · 14H2OMineralsulfate
- UranopolycraseUTi2O6Mineraloxide
- Uranosilite(UO2)Si7O15Mineralsilicate
- Uranospathite(Al,◻)(UO2)2F(PO4)2 · 20H2OMineralphosphate
- UranosphaeriteBi(UO2)O2(OH)Mineraloxide
- UranospiniteCa(UO2)2(AsO4)2 · 10H2OMineralphosphate
- Uranothorianite(Th,U)O2Variety—
- Uranothorite(Th,U)SiO4Variety—
- UranotungstiteBa(UO2)2W2O8(OH)2 · H2OMineralsulfate
- UreaCO(NH2)2Mineral—
- UriciteC5H4N4O3Mineral—
- Uroxite[(UO2)2(C2O4)(OH)2(H2O)2] · H2OMineral—
- UrusoviteCuAlO(AsO4)Mineralphosphate
- UrvantsevitePd(Bi,Pb)2Mineralsulfide
- UshkoviteMgFe3+2(PO4)2(OH)2 · 8H2OMineralphosphate
- UsoviteBa2CaMgAl2F14Mineralhalide
- UssingiteNa2AlSi3O8(OH)Mineralsilicate
- UstarasitePb(Bi,Sb)6S10Mineralsulfide
- UsturiteCa3(SbZr)(FeO4)3Mineraloxide
- UtahiteMgCu2+4Zn2Te6+3O14(OH)4 · 6H2OMineralsulfate
- Uvanite(UO2)2V5+6O17 · 15H2O (?)Mineraloxide
- UvaroviteCa3Cr2(SiO4)3Mineralsilicate
- UviteCaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3(OH)Mineralsilicate
- UytenbogaardtiteAg3AuS2Mineralsulfide
- UzoniteAs4S5Mineralsulfide