298 Classification of Massive Rocks. 
(B) quartz-mica-porphyrite, which contains quartz porphy- 
ritically developed. 
2. HoORNBLENDE-PORPHYRITES, containing hornblende as their 
‘most important iron-bearing porphyritic ingredient. 
According as these contain porphyritic quartz crys- 
tals or not, they are divided into :— 
(A) hornblende-porphyrite, quartz-free. 
(B) quartz-hornblende-porphyrite, quartz-bearing. 
3. ENSTATITE—PORPHYRITES, containing a rhombic pyroxene as a 
prominent porphyritic component. 
D. THE AUGITE-PORPHYRITES AND MELAPHYRES. 
This class corresponds to the gabbros and diabases among the 
intrusive rocks. Its members consist essentially of plagioclase and 
augite, and sometimes olivine, idiomorphically developed in a 
ground mass which may be either holocrystalline, hypocrystalline or 
lassy. According as the members of this group are olivine-free 
or olivine-bearing they are divided into :— 
1, AUGITE-PORPHYRITES, containing no olivine. This group 
embraces :— 
(A) diabase-porphyrite, possessing a panidiomorphic- or 
diabasic-granular groundmass of plagioclase and 
augite, 
(B) spilite, which is characterized by its fineness of grain 
and its lack of porphyritic constituents. 
(c) augite-porphyrite, having a fine-grained hypocrystalline 
ground mass in which are numerous porphyritic 
erystals of plagioclase and augite. Augite porphy- 
rite includes :— 
(e 1) labradorite-porphyrite, in which the porphyritic 
feldspar is labradorite and the ground mass 1$ 
composed of a second generation of augite and 
lath-shaped crystals of plagioclase and a very 
little glassy base. 
(c 2) weiselbergite, in which the ground mass is made 
up of a second and sometimes a third genera- 
tion of augite and slender needles of plagioclase, 
arranged in flow lines in a glassy base (hyalopt- 
litte structure). 
