| Earlandite | |
| Category: | Organic minerals |
| Formula: | [Ca<sub>3</sub>(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·2H2O |
| Imasymbol: | Ear[1] |
| Strunz: | 10.AC.15 |
| Symmetry: | P (No. 2) |
| Unit Cell: | a = 5.9466(4), b = 10.2247(8) c = 16.6496(13) [Å]; Z = 2 |
| Color: | White, pale yellow |
| Habit: | Nodular |
| Refractive: | nα = 1.515 nβ = 1.530 nγ = 1.580 |
| Opticalprop: | Biaxial (+) |
| 2V: | 60° |
| Birefringence: | δ = 0.065 |
| Streak: | White |
| Gravity: | 1.80–1.95 (measured), 2.00 (calculated) |
| Diagnostic: | Fine-grained and wart-like nodule crystal habit |
| Solubility: | Insoluble |
| Diaphaneity: | Transparent |
| References: | [2] [3] [4] [5] |
Earlandite, [Ca<sub>3</sub>(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·2H2O, is the mineral form of calcium citrate tetrahydrate. It was first reported in 1936 and named after the English microscopist and oceanographer Arthur Earland FRSE. Earlandite occurs as warty fine-grained nodules ca. 1 mm in size in bottom sediments of the Weddell Sea, off Antarctica.[4] Its crystal symmetry was first assigned as orthorhombic, then as monoclinic, and finally as triclinic.[2]