102 



regarded as an unnatural thing to keep the large axial ratio, 

 which is formed on the basis of the resemblance to parisite 

 and synchysite; if we divide the c-axis by 3, we shall get the 

 axial ratio: 



с = 1.1288, 

 and the following symbols: {40"45}, {lOTl}, {202l}, and{404l}i). 



The crystals of cordylite described here are, in contra- 

 distinction to those previously known, completely bright and 

 transparent with a yellowish colour. Pleochroism is distinctly 

 found; the colour of absorption is 



for rays vibrating parallelly to the c-axis, brownish yellow, 

 - - — perpendicular on — greenish yellow. 



No distinct difference is found in the degree of absorption 

 of the two directions. 



The interior of the crystals is completely homogeneous, 

 and no trace is seen of the peculiar, six-radiated structure, 

 described and figured by Flink. 



The determination of the indices of refraction is rather 

 difficult on account of the smallness of the crystals. By using 

 a face of c{000l} and a face of ^{юГз} at the other end of 



Very peculiar, although perhaps only due to chance, is the resem- 

 blance between this mineral and steenstrupite (which is, however, 

 markedly rhombohedral); the steenstrupite having the axial ratio 

 с = 1'0842 (cfr. Lorenzen: Medd. om Grønl. 2, 1881, p. 73; Moberg: 

 ibid. 20, 1898, p. 245, and Börgild: ibid. 24, 1900, p. 203) and pre- 

 dominantly the following four rhombohedra, which are developed in 

 almost all the crystals: {044o}, {lOllj, (022l|, and (404l}, that is 

 to say, exactly the same forms as in cordylite; further the base is 

 always highly developed, whereas JIOIOJ is wanting. The chemical 

 comparison between the minerals cannot be carried out in detail, as 

 the constitution of neither of them is quite known; the ratio between 

 the equivalents of SiO-i and Ce^O^ in steenstrupite agrees tolerably 

 well vv^ith CO.^ and Ce.^O^ in cordylite; the amount of (Mn, Ca) -\- 

 Na.^0 is somewhat greater in steenstrupite than BaO in Cordylite, 

 while the amount of Fis considerably smaller; this, however, has in 

 cordylite been determined as residue of a very small material for 

 analysis; the steenstrupite, moreover, contains some {Nb, P].^0-^ and 

 Hi 0, which may, hoAvever, possibly be unessential for the mineral. 



