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NEW YORK STATE MUSEUM 



minerals and is of common occurrence as grains or fragments in 

 many gold-bearing sands. It is found in many parte of Europe 

 and also in Maine and Georgia, at Magnet Cove Ark. and in 

 Orange count}', N. Y. 



Rutile is chiefly used to color porcelain and may serve as a 

 source of titanium. 



Octahedrite. Octahedrite is a tetragonal mineral of the same 

 composition as rutile but differs slightly from it in 

 crystallization. 



Brookite. Brookite is an orthorhombic form of titanium 

 dioxid closely related to the two foregoing minerals. 



Pyrolusite Mn0 2 



Pyrolusite is the dioxid of manganese and contains 36.8^ 

 oxygen and 63.2$ manganese. 



Pyrolusite commonly occurs in columnar masses which fre- 

 quently radiate from a center; also in fine grained massive 

 stalactitic and dendritic forms (pi. 8 2 ), in layers interposed with 

 psilomelane and in velvety, reniform crusts. It is black in color 

 and so soft (H-l-2.5) that it leaves a black mark on paper. The 

 luster is metallic or dull. 



Pyrolusite occurs associated with psilomelane, hematite, 

 limonite and manganite. It is found in central Europe, India, 

 Australia and Cuba; deposits occur in the United States in 

 Virginia, Georgia, Arkansas, California, Vermont and North 

 Carolina; Xew Brunswick and Xova Scotia furnish a high grade 

 material. 



Pyrolusite is used in the manufacture of various useful alloys, 

 as an oxidizing agent in the manufacture of chlorin, bromin and 

 disinfectants and in calico printing, glass coloring, etc. 



Gothite Fe 2 3 .H 2 



Gothite is a hydrated sesquioxid of iron and contains 27$ 

 oxygen, 62.9$ iron and 10.1^ w T ater. 



The orthorhombic crystals of gothite are prismatic in habit, 

 striated in the direction of the vertical axis and often flattened 

 in the direction of the brachyaxis into scales. Xeedlelike 

 crystals grouped in radiating or parallel position pass into mas- 

 sive featherlike structure and reniform and stalactitic forms. 



