xviii PREFACE TO THIRD SECTION 
limestone^ that, with respect to Greece, if we 
except the breccia formation around Mycen^, 
and in the substratum of the rock of the Acropolis 
at Athens, hardly any other substance can be 
found'. In the north of Greece, indeed, and 
in Macedonia, some very remarkable changes 
occur ; as, the serpentine breccia, or verde-anticOy 
in Thessaly; and that curious aggregate of 
dark diallage and white feldspar, called by 
Italian lapidaries " bianco e nero antico" in 
Macedonia. Other varieties of porphyry 
occur also in Thrace ; particularly one of 
hornblende porphyry, resembling lava, in the 
great plain of Chouagilarkir, near the foot of 
a chain of mountains called Karowlan, a branch 
of Rhodope. 
A contrary rule has been observed in writing 
the Supplement, which contains an account of the 
author's journey from Constantinople to Vienna. 
Here, as the subject related principally to 
the mines of Transylvania and Hungary, instead 
of compressing his mineralogical observations into 
the form of Notes, he was frequently compelled 
(1) Dr. Holland [Travels, &c. p. 397. Land. 1815.) thiuks "that 
t\i& ^vQdit limestone formation ol Greece and the Isles is particularly 
liable to the phcenoniena of earthquakes." 
