55- 



SAMUEL WEI OMAN 



III. 



IV 



SiO^ . . . . 



AlaOj... 



Fe.Oj.... 



FeO 



MnO 



MgO 



CaO 



Na^O... . 

 K,0 .... 



H,0 



CI 



F 



ZrO, 



Total 



76. 



54 

 82 



.62\ 



.../ 



.01 

 .85 

 •32 



67.90 



1.^-85 



5 • 36 



0.41 

 1. 78 

 3.21 

 4. Si 

 0.30 



61.18 

 19.72 



3-71 

 1.32 



trace 

 2.64 

 5.28 

 5.66 

 0.32 



99.67 



90.71 



99 • 83 



1 00 . 1 7 



54-79 

 22.87 



1.74 



3-24 



trace 

 1 .92 



trace 



10 -75 

 4.06 



0-S4 

 0,08 

 0.07 



99 • 75 



99-63 



I. Granite. Quarry granite known as the Wausau red granite. Consists 

 mainly of albite, orthoclase, and quartz. 



II. Amphibole granite (5298).^ Consists mainly of microperthite, quartz, 

 and an amphibole rich in ferric oxide, and alumina. 



III. Hedenbergite-quartz syenite (5917). Consists mainly of microperthite, 

 quartz, hedenbergite, arfvedsonite, lepidom.elane, and fayalite. 



IV. Amphibole syenite (601 1). Consists mainly of orthoclase and bluish- 

 green amphibole, and some magnetite, mica, fiuorite, and zircon. 



V. Sodalite-nepheline syenite (6426). Consists mainly of anorthoclase, 

 nepheline, sodalite, and hedenbergite, with some fiuorite. 



VI. Nepheline syenite (5829). Consists mainly of nepheline, orthoclase, 

 hedenbergite, and some fayalite. 



It should be understood that not all the phases of rock represented 

 in this alkali-rich series is indicated in the above table. Nor is the 

 range in content of silica supposed to be outlined, ^girite is a 

 common constituent of many of the rocks, but analyses of the aegirite- 

 bearing phases have not been made. Those who have studied the 

 alkali-rich magmas can best appreciate the amount of work necessary, 

 and the complexity of the problem met with, in describing these 

 interesting rocks from the mineralogical standpoint. Some of the 

 prevailing amphiboles, pyroxenes, and micas, as well as other minerals, 

 have been separated from the rocks and analyzed, and hence where 

 varietal names are used such use is based upon knowledge of the 

 chemical composition. The object of the present paper is merely 

 to describe the general character, occurrence, and signification of 



I The numbers refer to specimens in the Wisconsin Survey collection. 



