Earlandite

Earlandite
General
Category Organic mineral
Formula
(repeating unit)
[Ca3(C6H5O7)2(H2O)2]·2H2O
Strunz classification 10.AC.15
Crystal system Triclinic
Unknown space group
Unit cell a = 5.9466(4), b = 10.2247(8)
c = 16.6496(13) [Å]; Z = 2
Identification
Color White, pale yellow
Crystal habit Nodular
Streak White
Diaphaneity Transparent
Specific gravity 1.80–1.95 (measured), 2.00 (calculated)
Optical properties Biaxial (+)
Refractive index nα = 1.515
nβ = 1.530
nγ = 1.580
Birefringence δ = 0.065
2V angle 60°
Solubility Insoluble
References [1][2][3][4]

Earlandite [Ca3(C6H5O7)2(H2O)2]·2H2O is the mineral form of calcium citrate tetrahydrate. It was first reported in 1936 and named after the English microscopist Arthur Earland FRSE. Earlandite occurs as warty fine-grained nodules ca. 1 mm in size in bottom sediments of the Weddell Sea, off Antarctica.[3] Its crystal symmetry was first assigned as orthorhombic, then as monoclinic, and finally as triclinic.[1]

References

  1. 1 2 Herdtweck, Eberhardt; Kornprobst, Tobias; Sieber, Roland; Straver, Leo; Plank, Johann (2011). "Crystal Structure, Synthesis, and Properties of tri-Calcium di-Citrate tetra-Hydrate [Ca3(C6H5O7)2(H2O)2]·2H2O". Z. Anorg. Allgemeine Chemie. 637 (6): 655–659. doi:10.1002/zaac.201100088.
  2. Earlandite. Mindat.org
  3. 1 2 Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (2003). "Earlandite". Handbook of Mineralogy (PDF). V (Borates, Carbonates, Sulfates). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209740.
  4. Earlandite. Webmineral
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