300 Classification of Massive Rocks. 
1. LIPARITES, in which the porphyritic alkaline feldspar is sani- 
dine. These are divided into :— 
(A) nevadites, containing numerous porphyritic crystals 
and a ground mass whose structure forms the basis 
for a further subdivision into :— 
(a 1) nevadite, with a holocrystalline ground mass. 
(a 2) felso-nevadite, with a felsitic ground mass. 
(a 3) hyalo-nevadite, with a glassy ground mass. 
(B) liparites, containing few porphyritic crystals, and these 
few almost exclusively sanidine. These include :— 
(6 1) liparite, with a holocrystalline ground mass. 
(6 2) felso-liparite, with a felsitic ground mass, 
(c) hyalo-liparite, a glass with the composition of liparite, 
containing microlitic inclusions of sanidine, quartz 
and the iron-bearing silicates. 
2. PANTELLERITES, in which the porphyritic constituent is anor- 
thoclase. 3 
B. THE TRACHYTES AND QUARTZLESS PANTELLERITES. 
This group is characterized by the predominance of an alkaline 
feldspar among its porphyritic constituents, and its freedom from 
quartz. In addition to the feldspar there is usually an iron-bearing 
mineral porphyritically developed. 
Their structure, like that of the other effusive rocks, varies widely,, 
but always tends to the porphyritic. 
This group is divided into :— 
1. TRACHYTES, in which the porphyritic component is sanidine. 
The trachytes are next subdivided into :— 
(A)- trachyte, with a holocrystalline to hypocrystalline 
ground mass. 
(a 1) mica-trachyte, with sanidine and biotite as the 
most prominent porphyritic constituents. 
(a 2) augite-trachyte, in which augite replaces the bio- 
tite of (a 1). 
(B) phonolitic trachytes, differing from trachyte proper 
principally in the possession of the characteristic 
minerals of phonolite, viz., ægirine, acmite and 
sodalite. They include :— 
(b 1) sodalite-trachyte, which is rich in minerals of the 
alite group. 
