N. Z. ROCKS, 111 
B. a.—Acidic Igneous Rocks, Volcanic. 
13. Tracuyte Group, 
Compounds of Sanadine, Oligoclase (or even Albite 
and Labradorite), with some Hornblende or 
Augite and dark colored Mica; a rough mass in 
which some of the mineral constituents are fre- 
quently distinctly and separately developed and 
imbedded. 
a. Granular Trachyte. Mount Egmont, Taranaki. 
b, Porphyritic Trachyte. Sugar Loaf, Taranaki. 
¢, Compact Trachyte. Little Barrier Island. 
d. Vesicular Trachyte. Lyttelton Tunnel. 
Zt, Tvachy-dolerite. Great Barrier Island. 
14, Ruyouite Grove. 
Compact, enamel-like or vitreous matrix, enclosing 
grains or crystals of Sanadine, Oligoclase, Mica, 
or even Quartz. 
Aa, Common Trachyte Porphyry. Lake Taupo. 
Ab. Perlite-like Trachyte Porphyry. Taupo. 
Ac, Argilo-Trachyte Porphyry. White Island. 
Ad. Vesicular or Cavernous Trachyte Porphyry. 
Ruapehu, Taupo. 
Ae. Pumiceous Trachyte Porphyry. Taupo. 
Af. Slaty Trachyte Porphyry. Ruapehu, Taupo. 
ZB. Perlite. Rotorua. 
Ca. Common Obsidian. Mayor Island. 
Vb. Obsidian Porphyry. Mayor Island. 
Cc. Vesicular Pumice stone. Mayor Island. 
15. PHoNoLITE, OR CLINKSTONE Group, 
Compact, dark greenish grey matrix; gives a clear 
sound when struck by the hammer. 
a. Common Phonolite. Dunedin. 
6. Porphyritic Phonolite. Dunedin. 
¢. Trachytic Phonolite. Bell Hill, Otago, 
