| Steacyite | |
|---|---|
 Steacyite crystals from the type locality of Mont-Saint-Hilaire, Quebec | |
| General | |
| Category | Cyclosilicate |
| Formula | Kvariable(Ca,Na)2(Th,U)Si8O20 |
| IMA symbol | Scy [1] |
| Strunz classification | 9.CH.10 |
| Crystal system | Tetragonal |
| Crystal class | Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) |
| Space group | P4/mcc |
| Identification | |
| Color | Gray, dark brown, green, beige |
| Mohs scale hardness | 5 |
| Luster | Vitreous, greasy, dull |
| Diaphaneity | Translucent, opaque |
| Other characteristics |  Radioactive |
Steacyite is a complex silicate mineral containing thorium and uranium; formula K variable(Ca,Na)2(Th,U)Si 8 O 20. 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]
