139 
With regard to the minor accessories the ?ron ore is very 
limited in amount and sometimes entirely wanting. The biotite 
also is very scarce; it has a strong pleochroism varying be- 
tween a very dark brownish green and a light yellow-brown. 
Ægirine-augite is rare; it has only been observed in two spe- 
cimens where it occurs in rounded grains with the usual mar- 
ginal zone of ægirine and is surrounded by arfvedsonite in a 
parallel position. Astrophyllite has only been observed in one 
specimen; it is in groups of irregularly arranged laths less than 
0'8 millimeters long. This mineral has previously been found 
in somewhat larger crystals in different localities within the 
Julianehaab region!. The rinkite is rather common in this 
rock; it is often visible to the naked eye. In thin sections it 
is almost colourless and shows a polysynthetic twinning parallel 
to the cleavage; the extinction-angles of the lamellæ are very 
small. Steenstrupine in well defined crystals, reaching 0°5 
millimeters in length, occurs very sparingly. Between crossed 
nicols it shows the peculiar microstructure described by BöccıLo 
as pertaining to the crystals of his second type”, It is asso- 
ciated with colourless flakes of a mica which is supposed to 
be polylithionite because this mineral is an almost constant 
companion of the steenstrupine in the pegmatitic veins. Small 
crystals of fluorite are not uncommon in the sodalite-foyaite ; 
they are perfectly isotropic and colourless. Their index of 
refraction is perceptibly lower than that of sodalite, and this 
feature in connexion with the characteristic cleavage has been 
used for the identification of the mineral. It occurs in crystals, 
seldom more than 0'1 millimeter across, enclosed within the 
dark-coloured minerals. 
7 J. Lorenzen, Untersuchung einiger Mineralien aus Kangerdluarsuk. Zeit- 
schrift für Krystallographie IX, р. 253 (1884). O. В. BoGGiLD, On some 
Minerals from Narsarsuk (Meddelelser om Grønland XXXIII, 1906, р. 103) 
and Mineralogia Groenlandica (ibidem XXXII, 1905, p. 351). 
? 0. В. Воссию, New examinations of Steenstrupite. Meddelelser om 
Grenland XXIV, 1900, p. 208. 
