L 



SODA-POTASH SERIES, 

 ilica 65 to 55 per cent. : iron oxides 2h to 8 per cent. 1 

 i and magnesia together are more than half the alkalies, p 

 e than one-fifth of the alumina. Soda usually equal to 



SYENITE GROUP. 



Impounds of orthoclase and hornblende or biotite,. 



I augite. Quartz and plagioclase are usually present 

 ". o^^^.uiimue quantity, but sometimes the plagioclase may exceed 

 the orthoclase. 



Muscovite Syenite. 

 Preservation InIet~A fine to coarse grained rock, white or pale 

 pmk, with small muscovites scattered or in clusters. S.G. 2-64 - 

 -■62. Section : Quartz, orthoclase, plagioclase and muscovite. 

 The quartz is in small grains, from -01 to "04 in diameter, the last 

 not common, but shews no pressure granulation ; the larger grains 

 contam fine acicular, transparent, crystals. Orthoclase and 

 plagioclase are about equally abundant," and are from -02 to -07 

 m length. Pink garnets, about -015 in diameter are common. 

 Occurs on the periphery of the pink syenite found in Preservation 

 Inlet. An analysis by Professor Liversidge gave 65 per cent, of 

 silica ; (Trans. N.Z. Institute, Vol. x., p. 505) so it might equally 

 ^^ell be put into the Granite Group. 



reservation Inlet, Fiord Co. — A coarse grained pink rock. The 

 ^*'!'P^'; partly pink and partly white, forms the bulk of the rock, 

 J^'ith chlorite and hornblende in greenish black crystals, smaller 

 ilian the felspars, scattered tolerably evenly. Quartz in small 

 pantity. S.G. 2-635. Section : The Quartzes do not exceed -1 

 inch m diameter while the felspars are much larger. The latter 

 ij much decomposed, but I recognised plagioclase in the red and 

 orthoclase in the white felspar. The last, which is the least 

 aeconiposed, has numerous gas-pores in bands, principally in two 

 erections. The pink felspar is more abundant than the white, 

 ho n '^'^^^'^^^'^ ^y hfematite granules. Cleavage flakes of the 

 ^ orn ilende are slightly pleochroic,, changing from bluish-green to 

 ]• 'J^"jsli-green or yellowish-green ; with convergent polarised 

 ~'fit they shew a distorted optic axis and axial shadow. Most of 

 'f- hornblende however is altered to a green or l)rown chloritic 

 "neral, cleavage flakes of which are isotropic and shew no inter- 

 ^rence figure. Hutton. Geology of Otago, Dunedin, 1875, p. 4a 



