456 NATURAL HISTORY. 



fibrous structure within. H. = 5.0 to 5.5. G. = 3.6 

 to 3.8. Color all shades of brown, opaque ; streak yel- 

 lowish-brown ; luster sub-metallic ; often contains man- 

 ganese. The most important variety belonging to the 

 composition of Brown Hematite, is what is called Clay 

 Iron-stone, or lenticular argillaceous ore, consisting of 

 small oolitic or globular masses, of brownish color, and 

 flat, earthy fracture. Yellow ochre, another component 

 is earthy, loose, and is of a brown or yellow color ; occurs 

 in globular and stalactitic masses. Clay Iron-stone is of 

 dull color, impure, more or less earthy. Bog Iron ore 

 is found in globular or obtuse granular bodies of brownish- 

 yellow color ; loose, earthy ; and last of all is Umber, of 

 dark earth color, and altogether without luster. Brown 

 Hematite is one of the most valuable ores of iron. Found 

 in all the stratified mountain formations in Germany and 

 the Alps, occurring in the sand, loam, and clay strata. 

 Ocher and Umber are employed as common materials in 

 painting. Plate 32, fig. 4. Found also abundantly in 

 extensive beds in all the Middle States. 



Manganese Spar Brownstone occurs either in 

 compound crystals or slender pyramidal shapes ; also 

 granular, with particles coherent. Color iron-black ; 

 luster metalb'c, opaque ; streak black. H. = 2.0 to 2.5. 

 G. = 4.6 to 4.9. Frequently found associated with 

 Brown Hematite in Sweden, the Hartz, and Siberia. In 

 the United States it occurs in large masses in Massa- 

 chusetts and Maine. Employed by chemists in the pre- 

 paration of different oxydes and chlorine. Affords a 

 permanent glazing to stone ware, and is besides valuable 

 in giving coloring to glass ; also as forming acids used as 

 components of several medicines and various chemical 

 purposes. 



