CLASSIFICATION OF IGNEOUS ROCKS 



589 



III the Orders are formed by a double application of the plan of 

 fivefold division, resulting in nine Orders. 



Owing to the cumbersomeness of the phrases necessary to 

 describe Orders when the mineralogical group-names are 

 employed quantitatively, it is advisable to use abbreviated terms 

 mnemonic of these mineralogical groups. For these we suggest 

 the following syllables: guar, mnemonic of quartz; fel, mne- 

 monic of feldspar ; leu, mnemonic of leucite and nephelite, 

 which is understood to include the other standard feldspathoids, 

 sodalite and noselite. From these syllables, with the addition 

 of the proper quantitative prefixes already mentioned, are 

 formed adjectives descriptive of the several Orders as given 

 below. 



On account of the resemblance between the words feldspar 

 and feldspathoid, in such frequent use, we suggest for the latter 

 the term le?iad. 



quartz extreme, perquaric. 



quartz dominant, doquaric. 



quartz and feldspar equal, quarfelic. 



feldspar dominant over quartz, quardofelic. 



feldspar extreme, 



feldspar dominant over lenad, 



feldspar and lenad equal, 



lenad dominant, 



lenad extreme, 



perfelic. 



lendofelic. 



lenfelic. 



dolenic. 



perlenic. 



It will be noted that in Class III, in which the salic and 

 femic minerals are present in equal or nearly equal proportions, 



