104 



the erikite has been exposed to the influence of the atmosphere. 

 In other cases the crystals are partly or wholly rounded. 



Besides the minerals before mentioned crystals of steen- 

 strupite have also been found in a few cases in the same 

 veins as the erikite; the two minerals have not been found in 

 direct contact with each other. 



Chemical properties. 



By heating in a closed tube the mineral disengages water, 

 and becomes yellowish white; by the blowpipe its edges melt 

 to a whitish enamel. With salt of phosphorus it gives a pearl 

 slightly yellow when warm, by cooling colourless. It is decom- 

 posed by acids without gelatinization. 



In microscopical sections of the mineral when slightly 

 glowed, it is seen that the structure is chiefly unaltered; but 

 the colourless mineral (the hydronephelite) has completely dis- 

 appeared, so that the yellow ridges are seen especially distinctly. 

 The ingredients of the hydronephelite have probably been melted 

 together with those of the other mineral. 



Analysis has been made by cand. polyt. Chr. Christensen 

 with the following result: 



per ct. equiv. 



SiO^ 15-12 0-252 



F,_0^ 17-78 0-126 



(Ce, La, Di)oO.^ . . . 40-51 0-126 



ThO, " 3-26 0-008* 



Л/оОа 9-28 0-091 



CaO 1-81 0-032 



Na^ 5-63 0-091 



H^O (total) 6-28 0-349 



99-67 

 * Calculated as Th^O.^. 



The mineral loses at 110° Г29 per ct. oi H^O which is 

 again absorbed when it is left in open air. 



