276 
В. Agirine-tinguaite, Hedrum, Norway. V. Эенмегск, analyst 
(W. С. Brôccer, Die Eruptivgesteine des Kristianiagebietes I, 
1894, p. 191). 
preceding type, but its outer appearance is duller and the rock 
is evidently somewhat altered. 
The phenocrysts are very abundant. There are four kinds. 
The felspar phenocrysts are the most numerous; they are de- 
veloped tabular on (010), measuring about 12 millimeters by 2 
millimeters. The cleavage surfaces are dull, the colour is 
white or reddish. Under the microscope the large felspar 
tables are seen to be filled with a large number of small fel- 
spar crystals which apparently have originated by re-crystalli- 
zation. The low index of refraction proves that the felspars are 
alkali-felspars. Sometimes an indistinct microperthilic structure 
may be observed, but as a rule the felspars are too turbid for 
a closer determination. 
Fresh nepheline is not found as phenocrysts, but a number 
of pseudomorphs consisting of muscovite with some felspar 
must probably be derived from nepheline. 
A third kind of phenocrysts consists of an unknown colour- 
less mineral which shows some resemblance to cordierite, but 
differs in several respects. It occurs in rather equidimensional 
crystals, varying from 3 to 5 millimeters in diameter, which 
probably belong to the rhombic system. The crystals show a 
very marked lamellar structure in one direction, and two in- 
distinct cleavages perpendicular to one another and to the la- 
mellæ. Sections parallel to the lamella show tolerably hexa- 
gonal outlines, sections perpendicular to the lamelle are rect- 
angular. The hardness is about the same as that of nepheline, 
the specific gravity is 2°63. A negative optic bisectrix is per- 
pendicular to the lamellae; the plane of the optic axes is 
parallel to one of the cleavage directions; and the angle between 
the optic axes 2E is 25—30°. The mean index of refraction is 
