HuTTOX. — On the Foliated Bocks of Otago. 363 



sidered them as hornblende diorites ; but, as the hornblende 

 is in all cases allotriomorphic, it is probable that they were 

 originally augite diorites. 



Schistose Mica Diorite. 



George Sound. — A black-and-white coarsely-speckled rock, 

 indistinctly foliated, but not breaking easily along the plane 

 of foliation. Composed of feldspar— chiefly, if not entirely, 

 plagioclase — and biotite, with a little hornblende, the ferro- 

 magnesian minerals occupying less than half the rock. The 

 feldspars range up to O'lin. in length, but usually they do not 

 exceed 0-Oiin., while the biotites go up to 0-03in. A slight 

 pressure-granulation is visible. 



This is the rock of the Gertrude Waterfall, at the head of 

 the sound. 



Hornblende Diorite. 



Milford Sound. — A black-and-white coarsely-speckled rock ; 

 not foliated. Composed of plagioclase and hornblende, the 

 latter occupying less than half the rock. The plagioclase 

 crystals go up to 0-03in. in length, the hornblendes to O'Olin. 

 The feldspar shows pressure-granulation, and the hornblendes 

 are much broken up and granulated. 



From the boat-landing below Lake Ada, Arthur River. 



Schistose Hornblende Diorite. 



Milford Sound. — Coarsely-grained black-and-white-speckled 

 rocks with the foliation distinct, sometimes so pronounced as 

 to make the rock split readily along the plane of foliation. 

 Often containing pink garnets, sometimes large sometimes 

 small, in which case they are often clustered in bands, 

 averaging about iin. broad, lying in the plane of foliation. 

 The rocks are composed essentially of plagioclase and horn- 

 blende, with a little quartz and, occasionally, some muscovite. 

 The hornblende occupies from half to less than half the rock. 

 Spliene is often abundant. The feldspars go up to 0-04in. in 

 length, and the hornblendes to O'OGin. There is no appearance 

 of pressure-granulation, but the feldspars are often full of 

 inclusions. 



From Harrison's Cove, and from Metal Point, below Mitre 

 Peak. These rocks, which are very common in Milford Sound, 

 pass into gabbros. 



Dusky Sound. — A black-and-white fine-grained rock, dis- 

 tinctly foliated, and breaking readily along the plane of folia- 

 tion. Composed of plagioclase and hornblende, the latter 

 occupying rather less than half the rock. A small quantity of 

 quartz is also present. Sphene is abundant. The feldspars go 

 up to O'Oiin. in length, and the hornblendes to O-Ooin. No 

 pressure-granulation. 



