804 THE GEOLOGY OP MINNESOTA. 



[Syenyte. Diabase. Basalt. 



No. 1882. SYENYTE. 



From the precipitous cliff on the eastern side of the hill rising at the southwest corner of sec. 8, T. 63-3 

 W., Brute lake. 



Ref. Annual Report, xxii, page 11. 



Meg. Fine-grained, red, granitic rock, with some sub-porphyritic feldspars and 

 hornblendes. No section. 



Age. Cabotian. u. s. G. 



No. 1883. DIABASE. 



N. E. 14 N. E. % sec. 17, T. 63-3 W., Brule lake. 

 Ref. Annual Report, xxii, page 11. 



Meg. Fine grained, dense, nearly black. 



Mic. In a fine, much changed groundmass of secondary consolidation are a few 

 phenocrysts of feldspar of the primary consolidation. It is only possible to say that 

 the rock is a phase of the basic eruptives of the region, rather than a clastic, for 

 which purpose the collection was made. One section. 



Age. Cabotian. N. H. w. 



No. 1884. DIABASE. 



N. W. M N- E. M eec. 16, T. 63-3 W., Brute lake. 

 Ref. Annual Report, xxii, page 11. 



Meg. Similar to the last, but weathering reddish. 



Mir. Somewhat coarser and fresher, yet having considerable calcite and epiilofe 

 and zoisite as products of alteration. One section. 



Age. Cabotian. N. H. w. 



No. 1885. DIABASE. 



From an island in Brute lake, lying off the easternmost point in S. E. % S. W. J4 sec. 10, T. 63-3 W. 

 Ref. Annual Report, xxii, page 11. 



Meg. Resembling amygdaloid, the spots sometimes being one-half an inch in 

 diameter. The rock is also porphyritic with feldspar. 



Mic. Still coarser than the last, the feldspars of the second consolidation being 

 divergent. This rock was at first probably in part glassy, but the glass has been 

 replaced by products of alteration, such as hornblende, calcite, epidote, magnetite, hema- 

 tite and chlorite. One section. 



Age. Cabotian. N. H. w. 



No. 1888. BASALT. 



N. E. 14 sec. 18, T. 63-3 W., Brule lake, in the hills west of the lake. 

 Ref. Annual Report, xxii, page 12. 



Meg. Black, fine, apparently with fine quartz grains, slaty. 



Mic. This rock is similar to several others collected about Brule lake, but was 

 evidently more quickly cooled, and at first must have contained a considerable glass, 

 which is now replaced by some of the minerals enumerated under No. 1885. One section. 



Age. Cabotian. N. H. w. 



