| Corkite | |
| Category: | Phosphate minerals |
| Boxwidth: | 24 |
| Formula: | PbFe3[([[Oxygen|O]]H)6:SO4:PO4] |
| Imasymbol: | Cok[1] |
| Molweight: | 667.82 g/mol |
| Strunz: | 8.BL.05 |
| Dana: | 43.4.1.2 |
| System: | Trigonal |
| Class: | Ditrigonal pyramidal (3/m) (same H-M symbol) |
| Symmetry: | R3m |
| Unit Cell: | a = 7.3065(5) Å, c = 16.897(2) Å; V = 781.2 ų; Z = 3 |
| Color: | Brown to light yellowish brown, pale yellow, yellowish green to dark green |
| Habit: | Crystals pseudocubic rhombohedral with prominent . Commonly in crusts and massive |
| Cleavage: | Perfect on |
| Mohs: | 3.5–4.5 |
| Luster: | Vitreous, resinous |
| Refractive: | nω = 1.930 nε = 1.930 n = 1.93 – 1.96 |
| Opticalprop: | Uniaxial (−), may appear anomalously biaxial |
| Birefringence: | δ = 0.000 |
| Gravity: | 4.295 (measured), 4.31 (calculated) |
| Diaphaneity: | transparent |
| Other: | Readily soluble in warm HCl |
| References: | [2] [3] [4] [5] [6] |
Corkite is a phosphate mineral in the beudantite subgroup of the alunite group. Corkite is the phosphate analogue of beudantite and with it, a complete solid solution range exists. Corkite will also form a solid solution with kintoreite.
Corkite is named after County Cork, Ireland; the location where the first notable amount was discovered in 1869.[3] Like many of the other minerals in the beudantite group, corkite is a relatively uncommon, secondary mineral that occurs in oxidation zones near hydrothermal base metal deposits.[3] It occurs associated with pyromorphite, malachite, plumbojarosite, limonite and quartz.[6]