256 T. S. Hunt on Lithology. 
The minerals essential to the composition of the rocks under 
consideration are few in number, and are as follows: quartz, or 
thoclase; a triclinic feldspar which may be albite, oligoclase, an- 
desine, labradorite or anorthite ; scapolite, leucite, nepheline, so- 
dalite; natrolite, or some allied zeolite; iolite, garnet, epidote, 
wollastonite, hornblende, pyroxene, olivine, chloritoid, serpen- 
tine, diallage; muscovite, phlogopite, and some other micas; 
chlorite, and tale. To these may be added as accidental ingre- 
dients, the carbonates of lime, magnesia, and protoxyd of iron, 
together with magnetite, ilmenite and sphene. The silicates 
names. We may note first the granitoid structure, in which t 
mineral elements are distinctly crystalline, as in granite. From 
this, there is a gradual passage through granular into compact 
varieties of rock. Most of these are simply finely granular, and 
ee on this point Naumann On the probable eruptive origin 
several kinds of gneiss, etc.; Leonhard and Bronn, Neues Jahr. 
po es others icet d 
Scrope, is undoubtedly the result of movements in the ee 
mass, and the same is true of some of the granitoid dolorites 
? 
seems to a stud 
on already remarked, the progress of each year’s investiga 
2 to the category of indigenous rocks many ° th 
-Viously regarded as eruptive, and will, I am convinced, 
