974 ON A LEUCITE-BASALT FROM CENTRAL NEW SOUTH WALES, 



NOTE ON A LEUCITE-BASALT FROM CENTRAL NEW 



SOUTH WALES. 



By Rev. J. Milne Curran, F.G.S. 



The object of this note is to i^ecord the existence and discovery 

 of a Leucite-basalt — a i-ock hitherto unknown in Australia, and, 

 by giving publicity to the fact, to elicit some information as to its 

 existence in other parts of the colonies. 



Alexander von Humbolt is responsible for the opinion which 

 until lately was generally received, that leucite was a mineral 

 occurring only in Europe. Up to the present it has not been 

 found very widely distributed. It is found in the i-ecent Vesuvian 

 lavas, in the Eifel near Wehr, on the Laacher See, the Forstberg, 

 in the Thiiringerwald, Rohon Mountains, Olbriick, and in other 

 localities in Saxony and Bohemia, as well as at Capo di Bove, and 

 Frascati, near Rome. In 1875 Zirkel announced (Neu. Jahrb. f. 

 Mineral. 1875) that leucite was a constituent of a basaltic rock 

 in the island called Bawean, north of Java. This was the first and, 

 as far as I can find, the only example of an Asiatic leucite-basalt. 

 In 1876 Zirkel's " Microscopical Petrography " was published, and 

 in that work (p. 259), the existence of a leucite-rock from the 

 Wvoming Territorv of North America is recorded. 



More than two years ago I examined a basaltic hill a few miles 

 to the west of the railway line at Byerock, County of Cowper, 

 and on cutting some thin slices saw that the felspar I had expected 

 to find in the rock, was replaced by leucite. Afterwards from 

 information I received, I had reason to believe that the hill known 

 as El Capitan, situated about 30 miles to the north-east of Cobar, 

 in the County of Canbelego, consisted of basalt. Recently I 



