FE 
DESCRIPTION OF ROCKS AND ANALYSES 21 
; crysts strongly predominate, the medium olivine may be admitted 
as of hyalosideritic composition. The core of olivine contains no 
4 inclusions, only the outer envelop shows scarce rounded drops of 
brown perofskite. — The second place in order of crystallisation 
belongs to nephelite; only rarely he reaches the dimensions of true 
phenocrysts, and then in intimate connection with olivine, forming 
a parallel farther growth of idiomorphic olivine phenocrysts, as a 
colourless likewise idiomorphic shell. The crystallographic axes c 
of both individuals are parallel, thus the axis of optical symmetry 
w (nephelite) is parallel to ® (olivine). Yet generally the dimen- 
sions rest below 0.01 X 0.03 mm, and in contrast to the groundmass- 
nephelite he is free of inclusions;! by this means it is possible to 
distinguish the nephelite microphenocrysts from the groundmass 
ones nearly equal in dimensions: the latter shows abundant central 
inclusions of apatite, augite, and sparingly magnetite. Both refrac- 
tive indexes of the nephelite phenocrysts rise above the refractive 
power of the balsam (n= 1.5354), while for the groundmass ones 
were fixed «> 1.5354, o< 1.5354. Consequently a zonar structure with 
a core of higher refracting power was proved on the phenocrysts; 
perhaps the core contains some quantities of RO-oxides (BaO?). 
— The microphenocrysts of magnetite are either built up by glo- 
merophyritic accumulations of several inviduals to a rounded grain, 
or they show sharp octahedrons. He is later im order of crystal- 
lisation than the greater part of the olivine microphenocrysts, be- 
cause in glomerophyritic accumulations of olivine, which are sug- 
gestive of „olivine-bombs“, he forms the cement together with ne- 
phelite and analcite. Diminishing in dimensions he passes into 
the groundmass-magnetite. No sure tests upon titanium-content of 
the magnetite were shown, but his near relations to perofskite makes 
such a one probable. — The augite-microphenocrysts are pale yel- 
low with brown-purplish tints. The core is free from magnetite in- 
clusions, but contains short needles of apatite and square sections 
of nephelite; an outer zone is overloaded with magnetite inclusions 
