| Ralstonite | (Na,Mg,Al,F,OH,nH2O) |
| Rammelsbergite | NiAs2 |
| Ramsdellite | MnO2 |
| Realgar | AsS |
| Red Beryl | Be3Al2(SiO3)6 |
| Rheniite | ReS2 |
| Rhodizite | (K,Cs)Be4Al4(B,Be)12O28 |
| Rhodochrosite | MnCO3 |
| Rickardite | (Cu,Te) |
| Rinneite | (K,Na,Fe,Cl) |
| Roaldite | Fe4N |
| Robinsonite | Pb4Sb6S13 |
| Rock Crystal | SiO2 |
| Romanechite | Ba(Mn+2,Mn+4)5O10.H2 |
| Romeite | (Ca,Na,Fe,Mn,Sb,Ti,O,OH) |
| Rontgenite | Ca2(Ce,La)3(CO3)5F3 |
| Rosasite | (Cu,Zn)2(CO3)(OH)2 |
| Rose Quartz | SiO2 |
| Ruby | Al2O3 + Cr trace |
| Rutile | TiO2 |