The analyses of cerite made in the earlier part of the nineteenth century resulted in some confusion. Klaproth in 1807 found 34·5 per cent. SiO₂ in a specimen (his Ochroite); Vauquelin in 1805, and Hisinger in 1810, found 17·0 and 18·0 per cent. respectively.[19] Hermann[20] called attention to this discrepancy in 1843 (and again in 1861), and declared that the two could not be the same. For Klaproth’s mineral he proposed to revive the name Ochroite, whilst from his own analyses he proposed for the cerite of Berzelius the name Lanthanocerite, having found carbon dioxide and lanthanum, with much less cerium, in the latter.[21] In 1861 Kenngott partly explained these results by showing that the sample of cerite which Hermann had analysed contained Lanthanite[22]; but the extraordinarily high percentage of silica obtained by Klaproth remained unexplained. It may have been due to impurities of high silica content in the specimen he examined.
[19] Vide Hintze, Handbuch der Mineralogie, Leipzig, 1897, ii., 1329.
[20] Hermann, J. pr. Chem. 1843, 30, 194, and 1861, 82, 406.
[21] The announcement of the discovery of Lanthanum by Mosander was made in 1839.
[22] [Lanthanite] (see [list]) is an hydrated carbonate, R₂O₃,3CO₂,9H₂O, where R = cerium metals, chiefly Lanthanum.
Cerite contains from 59·4 to 71·8 per cent. of rare earths (oxides), the amount and nature of which vary with the precise locality. The oxides consist chiefly of ceria, lanthana, and didymia (praseodymia and neodymia), the complexity of the so-called ceria having been shown by Mosander in the case of ceria separated from gadolinite as well as from cerite; but yttria earths are also found to a small extent in the mineral.
It is remarkable that neither thorium nor uranium has been found in cerite, which is thus practically unique among the rare earth minerals.
This anomaly becomes even more marked in view of the very high percentage of inert gases found by Tschernik[23] in a related mineral from Batoum. This is a very complex mineral in which the basic part is represented by rare earths, chiefly ceria earths (50·8 per cent.) with water (3·4 per cent.), and oxides of iron, calcium and copper (6·8 per cent.); the acidic oxides being silica (6·6 per cent.), zirconia (11·6 per cent.), and titanium dioxide (14·7 per cent.), with phosphorus pentoxide (3·2 per cent.), and sulphuric anhydride (1·7 per cent.). Traces of thoria are present, but no uranium; very considerable quantities (up to 1 per cent.?) of helium were found.
[23] G. Tschernik, J. Russ. Phys. Chem. Soc. 1896, 28, 345; 1897, 29, 291. Abstracts in Zeitsch. Kryst. Min. 1899, 31, 513 and 514.
It is somewhat heavier than cerite (sp. gr. 5·08), but otherwise resembles it closely.