Apjohnite
Mn2+Al2(SO4)4 • 22H2O [CNMNC approved formula]
Named for James Apjohn (1796-1886), Professor of Chemistry and Mineralogy, Trinity College, Dublin, Ireland.
| IMA status : | Valid species (Pre-IMA 1838) Grandfathered |
| CLASSIFICATION | |
| Dana (8th edition) : |
29.07.03.03 |
| (29) Hydrated Acid and Sulfates | |
| (29.07) where A (B)2 (XO4)4 · x(H2O) | |
| (29.07.03) Halotrichite Group (Monoclinic with 22 H2O) | |
| Nickel-Strunz (10th edition) : |
07.CB.85 |
| (07) Sulfates (selenates, tellurates, chromates, molybdates, wolframates) | |
| (07.C) Sulfates (selenates, etc.) without Additional Anions, with H2O | |
| (07.CB) With only medium-sized cations | |
| Crystal system: | Monoclinic System |
| Point group (H-M): | 2/m — prismatic |
| Unit cell: | a = 6.198 Å, b = 24.347 Å, c = 21.266 Å, b = 100.28° |
| Crystal Habit: | Masses, crusts of fibrous or acicular crystals |
| Color: | Colorless, white, pale shades of yellow, green, pink |
| Diaphaneity: | Transparent |
| Luster: | Silky |
| Hardness (Mohs): | 1.5 |
| Measured Density: | 1.81 g/cm3 |
| Streak: | White |
| Geologic Setting: | As efflorescences. |
| Mineral Association: | Halotrichite, pickeringite, gunningite, copiapite, epsomite |
| Other Properties: | H2O Soluble. |
Origin: Pintados, Iquique, ChileSample size: 1.5 x 2 cm
Photo: Diederik Visser