THE DISTKICT OF SCHEMNITZ, HTTNGARY. 



309 



" hornblende-andesites " of the same area, with which they are so 

 intimately associated. 



In all these rocks it is interesting to find that the prevailing fel- 

 spar is always plagioclase ; in all of them orthoclase occurs only as 

 a subordinate ingredient, and hornblende and mica, or both of these 

 minerals together, form the next most important constituents ; and 

 in all of them grains of free quartz occasionally appear in the mass, 

 converting the " trachytes " into " dacites " and the " syenites " 

 (diorites) into " granites " (quartz-diorites). 



Rocks of precisely similar constitution to the so-called "granite 

 and syenite " of Hodritsch are very widely diffused in Hungary and 

 Transylvania, and in the countries lying southwards. In the 

 Vlegyasza, Bihar, and Eodnaer ranges in Transylvania, Dr. Doelter 

 has described the andesitcs and quartz-andesites as becoming 

 highly porphyritic, and even granitiform in structure*. The rock 

 of Illova Thai, which Richthofen compared with the " Nevadites " 

 of the Eocky Mountains, appears from the examples of it which I 

 was shown by Dr. Tschermak to be identical in character. In the 

 Bauat there occurs a precisely similar rock, to which Cotta applied 

 the name of " Banatite ;" and this forms intrusive masses which, as I 

 am informed by Prof. Szabo, are of clearly younger date than all the 

 members of the Cretaceous series. In the Euganean Hills we have 

 quartziferous hornblende-andesites which are certainly as recent 

 as the Eocene, if not of still later date. In the Alps we have the 

 granitic mass of the Adamello, for the rock of which Yom llath has 

 proposed the name of " Tonalite ; " and a rock of very similar cha- 

 racter from Queensland has been described by Daintree. In order 

 to illustrate the composition of these different granitic rocks, all 

 distinguished by the presence of free quartz with a triclinic felspar 

 as the predominating ingredient, I place side by side the following- 

 analyses : — 



I. Dacite (Quartz- II. Banatite 



Andesite) of Kis of Szaska, 



Sebes, Transyl- Hungary, 



vania (Doelter). (Scheerer). 



Silica 66-32 65-84 



Alumina 14-33 15-23 



Oxides of iron and 



manganese . . 5*78 3-50 



Lime 4-64 4-74 



Magnesia 2-45 2 31 



Potash 1-61 3-06 



Soda 3-90 2-96 



Loss 1-13 0-98 



III. Tonalite of 



the Adamello 



Group in the 



Alps (Vom 



Bath). 



66-91 

 15-20 



6-45 

 3-73 

 2-35 

 0-86 

 3-33 

 1-17 



IV. Quartzi- 

 ferous horn- 

 blende-ande- 

 sites, Euga- 

 nean Hills 

 (Vom Bath). 



67-98 

 13-05 



5-69 

 1-63 

 0-14 

 3-23 



7-96 

 0-32 



* " Zur Kenntnis8 der quartzfiihrenden Andesite in Siebenbiirgen und Un- 

 garn, von Dr. C. Doelter," Tschermak's Mineralogischen Mittheilungen, 1873, 

 p. 51. 



