Okaro, Tauranga Co. — A very dark grey, almost black rock, 

 -with irregular, angular, white inclusions ; no porphyritic crystals 

 visible. Section : Ground-mass abundant, crystallitic, globulitic, 

 containing numerous felspar laths up to "01 in length. Porphy- 

 ritic minerals are plagioclase, not common, up to -02 in length, 

 and magnetite. There is no fluxion structure. Enclosed are 

 angular fragments of a white, translucent or opaque, rhyolite, 

 between crystallitic and felsitic, perhaps kaolinised. Thrown out 

 of the ' Black Crater ' at Okaro, during the eruption of June 1886. 

 Hutton, Quart. Jour. Geol. Soc. of London, Yol. XLiii., p. 184. 



Professor Thomas has come to the conclusion that no Augite 

 Andesite was thrown out of the Black Crater during tlie eruption. 

 [Report of the Eruption of Tarawera, Wellington, 1888, p. 55.] 

 But angular fragments of non-scoriaceous andesite were found, so 

 far as I know, only near the Black Crater, and here on the 28th 

 June, I found them in abundance. On the 20th June Mr. H. 

 Boscawen saw stones thrown out of the north corner of the Black 

 Crater, some of which he picked up : two of these he gave to me, 

 and they were Augite Andesite. On Professor Thomas' theory 

 these stones must have been thrown out of Tarawera into the 

 Black Crater during the time it was in violent eruption on the 

 1 Gth June, and they must have remained in it for ten days not- 

 withstanding constant eruption. Also when I was at Okaro black 

 rock could be seen in the crater wall — indeed it was from this 

 that it got the name. Professor Thomas did not visit the locality 

 until three weeks later, when the black rock was probably covered 

 up by mud slips. 



Mt. Tarawera, Tauranga Co.— Black, highly vesicular, angular 

 fragments, sometimes containing angular fragments of a white 

 rock. Section : Ground-mass very abundant, crystallitic, globulitic 

 very opaque. Porphyritic minerals very scarce and small. Plagio- 

 clase in broken fragments up to -02 inch. Augite greenish yellow 

 in square prisms -02 in length. Contain fragments of decomposed 

 hornblende rhyolite passing into pumice. Thrown out of the 

 Mountain during the eruption of 10 June, 1886 ; picked up at 

 Pakaraka, and Galatea. Much like the last, but the rock itself 

 and the included fragments are much more vesicular. 



Te Aroha, Thames Distric 



' greenish, glassy, felspar. 



niass abundant, crystallitic, longulitic, with 

 niicrolites, not shewing fluxion. The porphyritic minerals ar 

 plagioclase, augite, and magnetite. The plagioclase is muel 

 decomposed, and goes up to -06 in length. The augite is idio 

 niorphie, pale yellowish, up to -02 in length. Secondary mineral 

 are chlorite and calcite. Waiorongomai River, just behind th< 



