| Steacyite | |
| Category: | Cyclosilicate |
| Imasymbol: | Scy[1] |
| Strunz: | 9.CH.10 |
| System: | Tetragonal |
| Class: | Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) |
| Symmetry: | P4/mcc |
| Color: | Gray, dark brown, green, beige |
| Mohs: | 5 |
| Luster: | Vitreous, greasy, dull |
| Diaphaneity: | Translucent, opaque |
| Other: | Radioactive |
Steacyite is a complex silicate mineral containing thorium and uranium; formula . It forms small brown or yellow green crystals, often cruciform twinned crystals. It is radioactive. It was discovered at Mont-Saint-Hilaire, Quebec in 1982 and is named after Harold Robert Steacy (1923–2012), mineralogist.[2]