APPENDIX. 6ol 



Micliilimackinac. Sometimes these crystals fill cavities or seams 

 of the rock, or are studded over the angular surfaces of masses of 

 vesicular limestone of that island, I also found this mineral at 

 Dubuque's mines, and in small crystals in the metalliferous lime- 

 stone bordering the Fox Kiver, between the post of Green Bay 

 and Winnebago Lake, where it is associated with iron pyrites 

 and blende. 



Subs. 2. — Compact Limestone. 



In proceeding northwest of Detroit, this mineral is first observed, 

 in situ, on an island in Lake Huron. It is afterwards found to 

 be the prevailing rock along the south and southwest shores of 

 Lake Huron. In many places, it incloses fossil remains. Some- 

 times it is earthy^ as at Bay De Noquet, a part of Green Bay, on 

 Lake Michigan, where it contains very perfect remains of the 

 terrebratula. (Parkinson.) In other places, no remains whatever 

 are visible, and the structure is firm and compact; or even passes, 

 by a further graduation, into transition-granular, of which, it is 

 believed, the west shores of Lake Michigan afford an instance. It 

 is most commonly based upon sandstone, which also contains, in 

 many places, the fossil organized remains of various species of 

 crustaceous animals, and of vegetables, sometimes, coal, &;c. 



Subs. 3. — Agaric Mineral. 



This mineral substance occurs in crevices and cavities in the 

 calcareous rock of the Island of Michilimackinac, Michigan. 



Subs. 4. — Concrete Carbonate of Lime. 



1. Calcareous Sinter. — In the form of stahct'des and stalagmites^ 

 in a cave situated near Prairie du Chien, on the Upper Mississippi. 



2. Calcareous Tufa. — A remarkable formation of tufa is seen 

 on the east banks of the Wabash River, near Wynemac's Tillage, 

 about ten miles above the junction of the Tippecanoe. It extends 

 for several miles, and is deposited to the thickness of thirty or 

 forty feet above the water, forming cliffs which are covered with 

 alluvial soil and sustain a growth of forest trees. The precise 

 points of its commencement and disappearance were not observed. 

 The structure is cellular or vesicular, and resembles, in some 

 places, a coarse dried mortar. It is very light, and possesses a 



