Mineralogical Contributions — Hobbs. 181 
ing on the limestone of the district. Its surface is botry- 
oidal and the mineral has the appearance of having been 
sublimed upon the surface. In color it is almost pure white 
resembling magnesite ; but ignited on charcoal it becomes 
yellow, cooling to white, and with cobalt solution gives the 
usual color of zinc compounds. It dissolves readily in hy- 
drochloric acid. 
f. Other Unreported Occurrences of Wisconsin Min- 
erals. Other minerals which are not upon record, and 
which have been found in Wisconsin are given below. 
Pyrrhotite from Mountain post office, where it is found 
in quite extensive deposits entirely massive in appearance. 
Barite from Belmont, which occurs with brown blades 
as imperfect crystals up to 4 or 5 centimeters in length. 
Limonite pseudomorphs after marcasite from Madison. 
These latter pseudomorphs show the combination of the 
prism m with either v or 1. 
Malachite; Baraboo, Sauk county. 
Chalcopyrite, cuprite, and malachite ; Boscobel. 
Chalcopyrite, malachite ; Soldier's Grove and Wayne. 
Graphite; Marshfield. 
g. Minerals from Helderberg Limestone of Tiffin, Ohio. 
The University of Wisconsin is indebted to professor M. E. 
Kleckner of Heidelberg university located at Tiffin, for a 
small collection of minerals from the quarries at that place. 
According to professor Kleckner the limestone of the dis- 
trict is part Niagara and part Helderberg, and it is in the 
latter that the crystallized minerals have been found. They 
occur as the lining of cavities some of which have a 
diameter, as indicated by specimens received, of one to two 
decimeters. Certain layers in one of the quarries have 
many filled cavities of cylindrical shape which have become 
known to the quarry-men as "plugs." These seldom ex- 
tend through more than a single layer of the limestone. 
The minerals of this plug are the same as those filling the 
other cavities; namely, calcite, celestite, fluorite, and sphal- 
erite. 
The calcite is the most abundant of the minerals lining 
the geodes, and occurs in two different habits. The first 
