| Strengite | |
| Formula: | FePO4·2H2O |
| Imasymbol: | Stg[1] |
| Molweight: | 186.85 g/mol |
| Strunz: | 8.CD.10 |
| Dana: | 40.04.01.02 |
| System: | Orthorhombic |
| Class: | Dipyramidal (mmm) H-M Symbol: (2/m 2/m 2/m) |
| Symmetry: | Pcab |
| Color: | Colorless, pale violet, deep violet, red, carmine red, greenish white |
| Habit: | Botryoidal, radial, spherical |
| Cleavage: | Good, Poor |
| Mohs: | 3.5–4 |
| Luster: | Vitreous |
| Streak: | White |
| Diaphaneity: | Transparent to translucent |
| Gravity: | 2.84 |
| Opticalprop: | Biaxial (+) |
| 2V: | 72° – 88° |
| Dispersion: | r < v, relatively strong |
| References: | [2] [3] [4] |
Strengite is a relatively rare iron phosphate mineral with the formula: FePO4·2H2O. The mineral is named after the German mineralogist (1830 - 1897). Lavender, pink or purple in hue, it is similar to variscite and is partially soluble, particularly in conditions where there is a low pH and low oxidation-reduction potential. The color comes from ferric ion (Fe3+).[5]