BUILDING STONES. 179 



Sandstones.] 



upon it. It also loses from one-sixth to one-third of its crushing strength. 

 The Dresbach quarry is owned by J. F. Tostevin, Jr., and was opened in 

 1881. It was the direct result of a visit by the state geologist, who, in 

 examining the "lead mine" 'of the Winona mining company, called atten- 

 tion to the quality of the excavated stone, comparing it with the Berea 

 sandstone of Ohio now largely imported to the state. The stone has not 

 yet been extensively introduced, but has been put into several buildings 

 in St. Paul and Minneapolis, and in the trimmings of Ladies Hall, one of 

 the buildings of Carleton college. It is confidently asserted by the own- 

 ers that this stone will successfully compete with the Ohio stone not only 

 in the country west of the Mississippi but even in the markets of Chicago 

 and Milwaukee. The Catholic church at Rollingstone, in Winona county, 

 is built from the St. Croix, but not quarried at Dresbach. 



Microscopic characters of No. 32. The grains are angular or sub-angular, and include some 

 that are f eldspathic. The latter retain a trace of cleavage in the parallel disposition of the lines of 

 minute impurities which darken them, and occasionally also show a minute striation as if triclinic. 

 The stone shows, in thin-section, frequent grains of green sand which have a closely netted inter- 

 nal structure, which in high powers shows an aggregation of globules. Scattered through the sec- 

 tion are conspicuous, elongated, nearly parallel, somewhat club-shaped, brown grains which are 

 probably sections of fragments of phosphatic bivalves. An occasional aggregation of minute pyrite 

 crystals may also be seen in reflected light. Muscovite is the only mica, and that is in very rare 

 scales. Ocher is nearly wanting in the gray-colored stone of Dresbach, but is much more frequent 

 in the weathered stone quarried at Dakota (No. 36) in the form of irregular clouds and patches. 



The stone quarried at Jordan, in Scott county (No. 33), is from the 

 typical locality of the Jordan sandstone formation, and is very similar in 

 all respects to the rock from Dresbach, except that it has a greater amount 

 of insoluble matter, and less of calcareous cement ; its alumina also is in 

 greater proportion. This rock is but little quarried in the state. Its line 

 of outcrop is quite narrow, being situated between two firm and persistent 

 limestones. Hence its superficial exposure is mostly confined to a turfed 

 slope along the bluffs of rivers near the top, just below the Shakopee lime- 

 stone. It is thus seen in numerous places in Fillmore, Olmsted, Winona 

 and Houston counties, at points some miles away from the Mississippi river. 

 It is not known at any place in the bluffs of the Mississippi south of Hastings. 

 It can be seen at Stillwater, in Washington county, and probably exists in 

 the second terrace flat at Nininger in Dakota county. Its outcrop at Jordan 

 is along Sand creek, and rises but few feet above the water. No other rock 

 formation is visible, and were it not for the relation in which it is placed 



