182 THE GEOLOGY OF MINNESOTA. 



[Lemont stone. 



very fine stone has been taken out. The product of this quarry is sent to 

 Winnipeg, where a Manitoba college is trimmed with it. 



This sandrock is seen in the Clark and Hunter blocks at Duluth, but 

 the principal structure of this material in the state is the Westminster 

 church at Minneapolis, illustrated by plate H. It has been used as trim- 

 mings in a few buildings both in Minneapolis and St. Paul. 



Microscopic characters of No. 34. About two-thirds of this rock consists of rounded and sub- 

 angular grains of quartz, the most of it being pure and limpid, but some of it having numerous 

 globular inclusions. Nine-tenths of the remainder may be regarded as feldspar. This is often 

 crowded and darkened by ocher and ferrite but is sometimes white and kaolinic. Occasionally 

 can be seen a fibrous, light-green, angular grain that has apparently resulted from hornblende or 

 from augite. A few fibrous serpentiuous partings surround and separate some of the feldspars. 

 Apatite spicules cut some of the quartz. A few black grains are magnetite. A little calcite is 

 distinguishable. 



The sandrock which has been somewhat quarried and used at Taylor's 

 Falls (No. 37) is very similar to that obtained at Jordan. It is of a light 

 color, rather friable on first quarrying, hardens on exposure, and is in heavy 

 natural strata from which blocks of any desired size may be taken. It be- 

 longs to the St. Croix formation, and is extensively exposed in the bluffs of 

 the St. Croix and Mississippi rivers, but in a higher horizon than the Dres- 

 bach stone. . 



7. STONES FROM OTHER STATES. 



Owing to the use of several building stones in St. Paul and Minneapolis, 

 and to some extent in Hastings, Faribault, Red Wing and Winona, from 

 other states, it has been thought best to include in the tests that have been 

 made, samples of these stones, in order to ascertain their qualities and com- 

 parative merits. The results are given in the general table. The pieces 

 selected for these tests were obtained from the blocks that have been sent 

 to Minnesota for use m some prominent structure, and may be taken as 

 rather above the average for quality for the respective stones. The tests 

 were made in exactly the same manner, and frequently in the same solu- 

 tion, and at the same moment, as the tests made of Minnesota stones. 



Of these the Lemont stone (No. 38), also frequently known as the Joliet 

 stone, from the Niagara formation, in Illinois, comes through the series of 

 tests with a higher rank on a scale of 100 than any of the others, being in 

 that respect on a par with the Minnesota dolomite (No. 13) furnished by the 



