BY H. C. RICHARDS. 163 



Iron-ore granules are not very abundant and they 

 seem irregular in outline. The glass is a pale-brown colour 

 and in some eases is thickly crowded with trichites &c., 

 but in others it is comparatively free from them. The 

 specific gravity is 2-57. 



Specimen 123.— Locality : Portion 18, parish of 

 Witherin. This flow forms a prominent cliff on the south- 

 west end of Tamborine Plateau, and is well seen in a 

 cliff in front of "Sir. D. Lahey's house. The flow is more 

 than 100 feet thick and gives rise to a precipice along the 

 edge of the plateau. The rock is dark grey with large 

 phenocrysts of a dark plagioclase. Microscopically it is 

 seen to be hyalopilitic although the amount of glassy 

 material is very small. The rock is perpatic and the 

 phenocrysts are plagioclase and augite. The plagioclase 

 is medium andesine, AbsjAn^g, and similar plagioclase 

 containing inclusions as described in the andesine from near 

 Point Danger occurs. The crystals containing the inclu- 

 sions are not so abundant in this rock, and augite is 

 frequently seen as the included material along with the 

 glass. {See Plate XIII. , fig. 5.) The augite phenocrysts 

 are pale brown in colour and occur in allotriomorphic 

 crystals up to 1 mm. in diameter. The groundmass is 

 made up principally of small lath-shaped plagioclases 

 showing lamellar twinning and having an extinction angle 

 agreeing with medium andesine, Ab3An2. Abundant 

 iri'egularly-shaped patches and rods of iron ores occur 

 through the rock. The specific gravity is 2-64. 



