284 ON THE TRANSMUTATION OF BOCKS, &c., 



various parts of the Hunter River basin, porcellanite containing 

 impressions of ferns of the coal epoch occur, and even at 

 Khanterintee (which name, I think, implies action of fire), above 

 the beach near Newcastle, there are similar appearances. In the 

 Illawarra the coal is sometimes converted into coke and 

 prismatised. The specimen now on the table came from the mine 

 at Bellambi. I saw the spot in the mine whence it came, and 

 doubt not it was affected by the trap dyke which traverses the 

 beds. 



At Rive de Gier, in France, near Lyons, there is a mountain 

 called St. Genis-Terre-Noire, where all the changes by coal on fire 

 are well exhibited. First, there is irisation ; then the coal becomes 

 cellular and full of cavities ; then harder and more brilliant ; 

 lastly, it passes to a coke with metallic lustre. The coal is thus 

 affected through several feet of thickness. 



Now, if we examine the coal seam in Nobby's Island at the 

 mouth of the Hunter, altered by the greenstone dyke that passes 

 through it, we shall see a similar transmutation. 



I obtained, several years ago, examples of irisated coal and 

 half-burnt shale from an old pit on the ascent to Mount Keera ; 

 and here you perceive the irisation. The same feature dis- 

 tinguishes the transmuted coal of New Caledonia, as shown 

 by the specimens before us, which I lately received from my 

 correspondent there, M. Garnier, the French Government 

 Geologist. I am not sure about the transmuting rock in that 

 island ; but in Illawarra it is basalt. Similarly, the coal-beds on 

 the Nattai, near the Fitzroy mine, have been affected by igneous 

 rocks ; and one variety is full of minute concretions of ferruginous 

 matter which look like seeds. 



I have already shown that in Illawarra the coal in one place 

 is prismatised. It is so in Spitzbergen, in the Arctic Ocean ; 

 but though it was supposed from certain fossil shells very like 

 some in our Australian lower Carboniferous beds, that the Spitz- 

 bergen coal was of that age, recent examination by Professor de 

 Koninck, of Liege, shows it to be of Permian age. 



Coal prismatised in this way passes sometimes from Coke to 

 Anthracite and Graphite. The whole of these sometimes occur 

 together, the graphite being nearest to the trap. 



