68 DISCOVERY REPORTS 



determination and shows that the nodules have a composition close to the theoretical 

 composition of hydrated calcium citrate, Ca3(C6H5 07)2.41^20. The departures are 

 probably due to adsorbed water and small variable amounts of impurities. A spectro- 

 graphic examination of the residue left after ignition of the second sample (4-075 mg.) 

 studied by Mr Hey shows in addition to calcium, traces of strontium, barium, mag- 

 nesium, manganese and iron ; also minute traces of copper (Plate II A, fig. 4). No 



Table III. Chemical analyses of eorlatidite, Cag (Cg H5 O- )2 . 4H2 O , from 

 St. 417, Weddell Sea, and of artificial calcium citrate 



impurity (except perhaps magnesium) amounts to more than o-oi per cent, e.g. the 

 phosphorus (probably present as phosphate) cannot be detected with certainty by 

 ordinary chemical methods. The nature of the small amounts of impurities in the cal- 

 cium citrate nodules is additional evidence that the nodules were formed at the sea- 

 bottom (J. V. Samoilov, 1917). Their distribution is even more restricted than calcium 

 oxalate and gypsum, and their origin is equally conjectural. So far as is known this is 

 the first reported occurrence of calcium citrate in nature. We therefore propose to name 

 the new mineral earlandite in recognition of Mr Arthur Earland's long-continued con- 

 tributions to the study of ocean deposits. 



SUMMARY 



Three crystalline components from the ocean bottom of the Weddell Sea have been 

 identified as crystals of calcium oxalate dihydrate, CaC204 . 2H2O, crystals of gypsum, 

 CaS04.2H20, and polycrystalline nodules of calcium citrate, Ca3(C6Hg07)2.4H20, for 

 which the name earlandite is proposed. X-ray photographs of the deep-sea crystals of 

 calcium oxalate show that the unit tetragonal cell has dimensions a 12-40, c 7-37 A. 

 and possesses the symmetry of the space-group CI,, = I 4/m. Crystals from renal calculi 

 yielding identical X-ray photographs are found to have the probable composition 

 CaCaOi . 2H2O. Both the deep-sea and renal calculi crystals are identical with, but larger 

 than "envelope" crystals found in the waste products of many plants and animals. The 

 trihydrate formula usually given to the "envelope" crystals is incorrect. 



