240 Wisconsin Academy of Sciences, Arts, and Letters. 



It is hence suggested that the term meta- be used as a prefix, when 

 it is desired briefly and conveniently to assert a metamorphic 

 origin ; that the prefix igno-hQ us3d similarly to assert an igneous 

 origin ; and aquo- in like manner, to imply an aqueous origin ; 

 while the simple terms shall have merely their own mineralogical, 

 or other appropriate, signification. 



Class V will then embrace the terms, lava and trap, used to 

 designate rocks of certain special eruptive origins, and a long list 

 of terms to which the prefixes meia , ingno- and aquo- are attached 

 to signify, respectively, metamorphic, igneous and aqueous origin. 



The foregoing terms furnish fair, though somewhat inadequate, 

 facilities for the designation of the several classes of properties 

 indicated under the headings. There remains to be added a series 

 of terms which shall express the mineralogical constitution of 

 rocks, which is by far their most important characteristic. It is 

 in respect to this that our present system is weakest, and, from the 

 fact that it attempts to impose fixed names upon indefinitely vary- 

 ing aggregations, must necessarily ever remain unsatisfactory. It 

 is, therefore, proposed to escape this difficulty by the use of a 

 system of flexible compound terms, which shall admit of varia- 

 tion to express varying composiiion, and, roughly, the varying 

 quantitative relations of the mineral ingredients. As above in- 

 dicated, the growing tendency in lithological literature is toward 

 the employment of compounds of mineralogical names. The 

 advantage of this, in clearness and precision, as well as in the con- 

 venience of the reader, is manifest. But it results in cumbersome 

 terms, and if canned sufficiently far to overcome the defects of 

 the present system, becomes burdensome. This, however, may 

 be obviated by a series of contractions which shall retain a sig- 

 nificant portion of the mineralogical name, without the burden of 

 its entirety. For the sake of euphonious combinations, these con- 

 tractions may be varied somewhat in their several combinations. 

 The following are suggested as available abbreviations of the 

 names of the leading minerals that enter into the composition of 

 rocks, and it will not be difficult to extend the list to any other 

 minerals that may, in given instances, become prominent litholog- 

 ical constituents. 



