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>]÷2H<sub>2</sub>O, 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. Its crystal symmetry was first assigned as orthorhombic, then as monoclinic, and finally as triclinic.