Journal Royal Society oj N.S. W., Vol. XXXV., 1901. 



Plate I. 



tfgk&fr 





Fig. 1. General aspect of the nephelinitic tinguaite of Kosciusko in ordinary light. 

 The dark aggregates are segirine-augite. The white rectangular or hexa- 

 gonal patches are nepheline. X 17 diameters. 



Fig. 2. The above rock seen under crossed nicols. ~ X 17 diameters. 





.4 * 



m 





^., 



Fig. 3. Similar to Fig. 1 but X 35 diameters. 



Fig. 4. Twinned crystal of sanidine '53 mm. X 118 mm. Enclosed in a pseudo- 

 porphyritic crystal of nepheline, in the nephelinitic tinguaite of Kosciusko. 



