WJiRNElUAN SVi^TEM. 
£C9 
With respect to compositioii, rocks are divided by Werner 
to simple and aggregated the former, consisting of unmixed 
nple minerals, are named and described according to his 
yctognastic system ; and to express the structure of those 
the latter division, he has framed a new descriptive language, 
liich has been very highly praised by his pupils, and to which, 
transferred from the original German by Mr. Jameson, per- 
ps the strongest objection is the harshness of its terms. The 
ecies of aggregated locks are about eighteen in number j the 
tiple, including those detailed in the formations of the newest 
Dctz-trap, are about thirty-five ; and if the various compo- 
nts of the aggregates, tejecting the less important, bt? included 
the enumeration, the total number of mineral species con- 
tuting the great mass of the globe, will not amount to more 
an twenty-five or thirty. 
The selection of the compounds which Werner has chosen 
• his species of rocks, is founded entirely upon their 
portance i that is to say, upon the distinctness and extent 
the masses which they present in nature, when viewed on 
} great scale. Several combinations of the simple minerals 
ing thus judiciously considered merely as varieties of the 
ire important ones. The propriety of the selection is pro- 
rtioned to the extent and fidelity of the observations of this 
uralist j but several of his species must still be regarded as 
ivisional, which future inquiries will modify and improve. 
The nomenclature of rocks adopted by Werner, has not been 
•y happily chosen. In a branch of knowledge founded, like 
• mineralogy of the German school, on materials brought 
ether by unenlightened labourers, much barbarism of names 
•s naturally to be expected. A reformer must have been 
itent to compromise between the principles of correct no- 
nclature, and the authority of terms already sanctioned by 
tom. Accordingly, in those formed and selected by Werner, 
unity of system is not to be looked for j some of the names, 
haps the best of them, being virtually insignificant, while 
ers are grounded on characters extremely variable and un- 
oortant. Of the latter description those derived from colour 
are 
Description of 
rocks as to 
tlicir composi- 
tion. 
.‘'pccies of 
U'crncrfmnul- 
ed upon their 
gcomiosliclim- 
puriance. 
Nomenclature 
not happily 
chosen ; tenns 
authorized by 
custom bcin" 
necessarily ad- 
mitted. 
( 
