1242 
is characterised by the occurrence of a very great number of little 
columns of gold-coloured aegirine-augite and of a few larger crystals 
with yellow margin which are mixed with feldspar, consisting partly 
of kalifeldspar, partly of plagioclase. 
In this transition-zone we find only a very little quantity of ore, 
whereas the larger augite crystals with yellow margin have after all 
originated from phenocrysts of the leucitite. Very near to the contact 
we find the original plagioclases of the enclosure as an opaque central 
portion in the neogenic feldspars; whereas at a short distance the 
original plagioclases have been conserved as such, and the neogenic 
minerals have been crystallized in small cavities of the rock. The 
appearance of the ore points to chemical interchanging of elements 
between the lava and enclosures; the gold colour and the modified 
optical properties of the augite and likewise the crystallization of 
neogenic minerals to a great distance from the contactzone of the 
enclosure which has become partly porous, indicate the influence of 
pneumatolytic gases. Leucite-tephrites of the Somma metamorphosed 
by fumaroles show very similar modifications. 
That in the contact-zone really melting has taken place is in such- 
like enclosures often proved by the fact, that the transition-zone 
penetrates tongue-shaped into the magma which has been crystallized 
as leucitite. Macroscopically the line of demarcation be'-veen the 
transition-zone which is only a few millimeters wide, and the leucitite 
can often easily be followed by the rapidly deereasing of the percentage 
of ore, and by the colour which for this reason becomes lighter. 
Among the smaller enclosures there are numerous ones, which 
have entirely been altered into a very porous rock, have obtained 
a yellowish colour, and contain besides the colourless neogenic 
minerals and the yellow pyroxene also a few crystals of haematite 
which macroscopically are perceptible as little black specks. 
In a larger enclosure with a diameter of about 20 centimeters 
the transition-zone was hardly brighter in colour than the leucitite, 
and this fact appeared to be accompanied by a much more gradual 
diminution of the percentage of ore. Moreover the augite shows no 
change of colour, and neither do we find the gold-yellow augite in 
the enclosure at some distance from the contact, notwithstanding 
the porous structure and the crystallization of pneumatolytic minerals. 
In the transition-zone little, but likewise much larger crystals of 
neogenie kalifeldspar and zonular plagioclase can be observed, enclosing 
the ore and the little columns and larger crystals of unmodified 
augite. In this contact-zone again borders of neogenic feldspar appear 
around the opaque plagioclases of the enclosure. 
