103 



comparatively large individuals of a diameter of 1 — 2'='°, but 

 also numerous quite small crystals of a diameter of 1 — 2™"i 

 are found, frequently provided with well developed bright faces. 

 The aegirine is rarely found in larger individuals, but most 

 frequently as fine, needle-shaped crystals generally forming an 

 entangled network. The relation between the erikite and these 

 two minerals with regard to age is varying; the needles of 

 aegirine, however, are always formed before or contempora- 

 neously with the crystals of erikite so as to interrupt the cry- 

 stalline faces of this mineral, and this feature also sometimes 

 holds good with regard to the smaller crystals of arfvedsonite. 

 The mentioned zeohtes are always younger than the other 

 minerals ; the analcite is never formed in crystals, but fills up 

 most of the interjacent spaces between the ingredients before 

 mentioned; it is colourless, and with marked right-angled clea- 

 vage in three directions. The nalrolite is found as very small 

 crystals covering all the walls of the remaining cavities as a 

 thin crust. The crystals are formed as very short prisms, 

 sometimes also as double pyramids, when the prismatic faces 

 are quite wanting, which form, otherwise very far from the 

 common form of the natrolite, is also found in the other 

 pegmatitic veins of the sodalite-syenite. When this crust of 

 crystals of natrolite is removed with a knife , the before men- 

 tioned, fine crystals of arfvedsonite is often seen under it. 



A smaller part of the crystals of erikite is found freely 

 projecting in cavities in the lujavrite. One end of the crystals 

 is grown fast in the lujavrite; between them the same minerals 

 are found as before mentioned. The appearance is somewhat 

 different from that of the crystals described above; the form is 

 sometimes lengthened after the c-axis; but otherwise the same 

 combinations as before mentioned are found. Some of the 

 crystals, especially the smaller ones, are very finely and regu- 

 larly developed. The faces are always dull, and the colour is 

 somewhat lighter than that described above, probably because 



