ISLAND OF PATMOS. 
itself, upon a nearer examination, proved 
to be a very curious porphyry: the nuclei were 
all of them intersecting crystals of feldspar, 
imbedded in decomposing trap 1 . Among the 
geological phenomena of the Archipelago, it is 
perhaps impossible to point out any that are 
more worthy of observation than those which 
are exhibited in the cliffs surrounding this 
remarkable harbour; and there has never been 
exhibited specimens of porphyry where the crys- 
tals of feldspar are in any degree comparable in 
size with those which are now mentioned*. 
(1) We succeeded in detaching some of those twin crystals, tolerably 
entire : their intersection bad taken place obliquely in the direction 
of their lateral planes, the major diameter of each crystal being 1 
parallel to that of its associate. Owing to this intersection, the 
appearance of a cross was exhibited whenever the nuclei, by weathering, 
had been worn away transversely, so as to become level with the 
superficies of the rock in which they were imbedded. This relative 
position and their colour give them some resemblance to leueite > 
differing from leitcite, otherwise, in the size and shape of the crystals. 
Leucile is, however, so nearly allied to feldspar, that were it not for 
the very minute portion of lime which is found iu the latter, their 
chemical constituents would be nearly the same, and in the same 
proportions; and possibly the double cleavage observed by Hauy in 
the former, which caused him to bestow upon it the name of amphi- 
gene, may lie owing to some circumstance of intersection which so 
commonly characterizes the crystals of feldspar. At all events, it 
may be proposed as a minerulogical query, " Whether, if lewitebc 
found before it has sustained the action of fire, it do not prove to be a 
variety of Adularia ? " 
(2) Martin Crutius, in his annotations upon an Epistle of Jlfacariiu 
(abbot of Palmoi) to the Creek Patriarch, in 1579, has cited a work 
printed 
