Lanthanite occurs with cerite at Bastnäs, and at Bethlehem, Pennsylvania. Morton[94] states that he prepared a crystalline didymium carbonate in the laboratory, of the formula Di₂(CO₃)₃,8H₂O, which was isomorphous with lanthanite; he concluded that the latter had only eight instead of nine molecules of water. [94] See abstract in _Zeitsch. Kryst. Min._ 1886-87, ~12~, 518. ~Parisite~ (~Synchisite~), and ~Cordylite~.--_Parisite_ is a fluocarbonate of calcium and cerium metals; _Cordylite_ is an analogous compound in which barium replaces calcium, and is isomorphous with Parisite. The formula of Parisite is CaR₂F₂(CO₃)₃, where R = cerium metals. Groth formulates this as (CaF)(RF)R(CO₃)₃, Penfield and Warren as (RF)₂Ca(CO₃)₃, whilst Schilling gives Ce₂(CO₃)₃,CaF₂. Analogous formulæ may be proposed for Cordylite, BaR₂F₂(CO₃)₃. Since the two minerals are very similar in crystallographic properties, one description will be sufficient for both. The following are Dana’s data for Parisite: Hexagonal, _c_ = 3·2891. (0001) ∧ (101̅1) = 75° 15´. Forms are extremely numerous, and have remarkably high indices. Among the simplest are the base _c_ {0001}, the prism _m_ {101̅0}, pyramids _q_ {101̅2}, and _h_ {112̅2}; the other forms are chiefly rhombohedra and pyramids. The usual habit is that of an acute double hexagonal pyramid, with form _o_ {202̅1}, terminated by _c_. Cleavage ∥ _c_, perfect. It is brownish-yellow to red. Hardness 4¹⁄₂; sp. gr. 4·36. The double refraction is strong, positive. Soluble in hydrochloric acid with effervescence. Both minerals are characteristic pneumatolytic species of the riebeckite-ægirine rocks. Parisite was discovered by Paris in the emerald mines of the Muso valley, Colombia, in 1835, and first correctly analysed by Bunsen in 1845. Before the blowpipe it glows, remaining infusible (the glow does not appear to have been investigated in this case). _Cordylite_ was discovered by Flink in 1900, in Greenland. It is yellow to brownish-yellow and colourless. Hardness 4¹⁄₂; sp. gr. 4·31. Before the blowpipe it decrepitates, and is infusible; moistened with hydrochloric acid, it gives the characteristic barium flame. The so-called Synchisite was discovered by Nordenskiöld who correctly described it as Parisite. Flink found it in Greenland, and announced it as a new species, with the formula R₂F₂Ca₂(CO₃)₄, _i.e._ the formula for parisite plus one molecule of calcium carbonate, CaCO₃. From its extraordinary resemblance to parisite in physical and crystallographic properties, Palache and Warren[95] believe that the specimens selected by Flink for analysis must have consisted, in reality, of parisite with admixed calcium carbonate. This conclusion has now been confirmed by Quercigh, by a careful comparison of the optical properties.[96] The minerals are usually found together, the chief localities being S. Norway, the gold districts of the Urals, Narsarsuk in S. Greenland, and Montana, U.S.A.