162 
case the original shape of the crystals is easily discernible be- 
cause most of them are surrounded by egirine-needles which 
are uninfluenced by the zeolitization’. In different slices of one 
single hand-specimen instances of all stages of conversion may 
not infrequently be found. The analcime formed in this way 
shows a low birefringence with an irregular and often finely 
lamellar distribution of the doubly refracting areas. It also 
exhibits a distinct cubic cleavage, and the directions of the 
cleavage-cracks indicate that the crystallographic orientation of 
the analcime very often keeps constant throughout each pseu- 
domorph and not seldom in the adjoining pseudomorphs also. 
The same holds good in those cases, too, where the original 
crystals have been bent or broken. Hence it follows that the 
transformation of the felspars into analcime is subsequent to 
the dynamical effects. 
Nepheline occurs rather abundantly in crystals giving square 
or hexagonal sections, commonly I or 2 millimeters across. It 
does not show any sign of mechanical deformation, but the 
crystals have been more or less rounded by magmatic resorp- 
tion. The ends of the felspar-laths sometimes project into the 
nepheline and not seldom small crystals of felspar and eudialyte 
are entirely included within it; besides, it contains numerous 
minute prisms of arfvedsonite and ægirine. 
A marginal zone of sodalite, probably due to some kind of 
resorption-process, has been observed surrounding the nephe- 
line in some specimens of the egirine-lujavrite. The sodalite 
was tested according to the method of Lamsrre*?. More com- 
monly the nepheline has been transformed into analcime. This 
process, too, commences at the margin of the crystals, and it 
т The conversion of felspar into analcime has been described in Meddelel- 
ser om Grønland XIV, р. 105 and Pl. V (1894). — A similar extensive 
formation of analcime at the expense of felspar and other salic miner- 
als also characterizes some of the Transvaal lujavrites (Н. A. BROUWER, 
Op. cit. pp. 130, 147). 
Zeitschrift der deutschen geologischen Gesellschaft, XLII р. 737 (1890). 
