138 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



sible under the circumstances. Some very imperfect 

 crystals of barite, in part colored brown by oxide of iron, 

 have been collected by Mr. L. S. Cheney from Belmont, 

 Wisconsin. 



MARCASITE FROM LINDEN MINE, CROW BRANCH MINE, 



MINERAL POINT, DIAMOND GROVE, HAZEL 



GREEN, AND GALENA. 



The mineral marcasite is found at many localities in the 

 Galena limestone, and seems to be of much more common oc- 

 currence there than pyrite. It appears under a variety of 

 forms. It is sometimes found as a cryptocrystalline to crys- 

 talline coating on the surface of galena or blende, and it also 

 occurs in well formed crystals, the University Collection in- 

 cluding a good suite of specimens from the several locali- 

 ties These crystals of marcasite show as great variety in 

 habit and combination as the massive and cryptocrystal- 

 line varieties show in their shapes. At least seven differ- 

 ent types of crystals have been observed on the specimens 

 in the University Collection. These will be described in 

 detail below. Their distribution is indicated in the follow- 

 ing list: 



Type 1. Linden Mine, Crow Branch Mine, and 

 Mineral Point. 



Type 2. Linden Mine. 



Type 3. Diamond Grove. 



Type b. Hazel Green. 



Type 5. Hazel Green. 



Type 6. Galena. 



Type 7. Galena. 



Type 1. Crystals of this type have a thin tabular habit 

 and are bounded by the forms c, OP (001); m, ooP (110) ; I, 

 Poo (Oil), and v, iPoo (013). (See plate 8, fig. 1.) The base 

 is as usual the plane of tabular development, and the edge 

 I : I at the extremity of the 6 axis is about as long as the 



