HYDROUS PEROXIDE OF IRON. 29 



HYDROUS PEROXIDE OF IRON. Thomson. 



Limonite. Bmdttnt and SAepurd. — Brown Oxide of Iron, and Argillaceous Oxide of Iron. Cleatieland. — Rhombohedral 

 Iron Ore. /omeson. — Hydrous Oxide of Iron. PAiUips. — Rhomboedrischea Eisen-Erz. itfoA«. — Brown lion Ore. 

 Dana. (It includes Brown Hematite, Brown Ochre, Umber, Yellow Iron Stone, Brown Clay Iron Stone, and all 

 the varieties of Bog Iron Ore.) 



Under the general name of Hydrous Peroxide of Iron, or Limonite, are now included the 

 several species and varieties above mentioned ; for the reason, as in the case of the Specular 

 Oxide, that all these minerals run into each other in such a manner as to baffle all attempts to 

 give distinctive characters. 



Description. Colours various shades of brown, soinetimes yellowish. Powder yellowish 

 brovra. Without action on the magnet. 



Very rarely occurs crystaUized ; it usually presents stalatitic, botryoidal or mammillary 

 forms, having a fibrous structure ; also massive, and sometimes earthy. When crystallized, 

 the primary form is said to be a right rectangular prism, but its occurrence in crystals has 

 been doubted by many mineralogists. 



Hardness, when pure, 4.5 to 5 ; in its impure form, its hardness is very variable. Specific 

 gravity 3.922 {Haidinger) ; 3.37 to 3.94 (Beudant). 



Infusible by the blowpipe, but gives out water by calcination ; and most of the varieties 

 become black or reddish black, and magnetic. With borax, it melts into a green or yellow 

 glass ; and it is soluble in heated nitro-muriatic acid. 



Composition. Limonite is supposed to be a hydrate of the peroxide of iron, the proportions 

 being 85.30 peroxide of iron, and 14.70 of water ; so that in its purest form, 100 parts of the 

 ore contain 59.70 metallic iron. There are, however, generally foimd in it various other 

 substances, either in mixture or in combination ; as silica, alumina, oxide of manganese, and 

 some ore of zinc. Titanium is also occasionally associated with it. It is sometimes mistaken 

 for the oxide of manganese, but the chemical characters are sufficiently distinctive. 



This mineral is here very widely and abundantly diifused. It is one of the most important 

 of our ores, and furnishes a considerable proportion of the iron at present produced in this 

 State. 



I shall now notice some of the principal localities of this ore, commencing in the southern 

 part of the State, and proceeding towards the north and west. 



Richmond County. Five or six miles southwest of the Quarantine, on the road to Rich- 

 mond village, there are beds of brown hematite, of some extent. The ore is sometimes 

 massive, and at others consists of spherical grains of various sizes, united by a ferruginous 

 cement, and known by the name of shot ore. It often has a shining surface, and appears to 

 be mixed and coated with talc. Brown and yellow ochres are also found here, and are used 

 by the inhabitants as paints. 



