145 
may reach a length of 1 or 2 centimeters. As a rule the 
sodalite is quite fresh, translucent, and of a greenish colour 
(rarely colourless). In polarized light it proves strictly isotropic. 
Lorenzex s analysis of this sodalite is here quoted: 
Analysis of sodalite-crystals of naujaite’. 
SiO Smee ee ae 36°50 
AS Ogee rae otra ea. ee 31°53 
Em aude cet 19 
CADET ER Fe 25 
NAS OFS ern ears 26°30 
ао емо eee 18 
Ol Ser 7°30 
102°25 
CH= ORR ane cere 1:65 
Total... 100°60 
SD ET. 2-31 
The sodalite-crystals contain innumerable minute needles 
or microlites of arfvedsonite and ægirine which are responsible 
for the greenish colour of the crystals. As a rule the arfved- 
sonite-needles are more abundant than the ægirine-needles. Their 
dimensions are very small, exceptionally they may reach a 
length of 0°05 millimeters and a thickness of 0°01 millimeters. 
Most of them lie parallel to the cleavage directions, but they 
do not show any zonary arrangement, with the exception that 
the marginal zone of the sodalite-erystals in some cases is 
free from microlites. Minute fluid-inclusions with a mobile 
bubble occur in large number; these are at least partly of 
secondary origin, for they are often arranged in long rows 
stretching across several crystals. The sodalite is sometimes 
found to be partially converted into analcime, but the com- 
monest alteration-product is natrolite-spreustein. Even in the 
freshest rock-specimens the microscope reveals the presence 
of small patches of natrolite at the margin of the sodalite- 
crystals; these patches appear just at the boundary between 
! Meddelelser om Grønland Il, р. 59 (1881). 
XXX VIII. 10 
