608 MANUAL OF NATURAL HISTORY. 



H. = 0*5 -3*5, dull black; 5, also as Silicate, 

 Carbonate, or Phosphate. Manganese com- 

 pounds form with borax in the outer flame of 

 the blov^-pipe a clear violet-red glass, which 

 becomes colourless on being exposed to the 

 inner flame ; with soda or platinum, the oxide 

 gives a green colour. Symb. Mn. 

 11. Family. — Siderides. Minerals containing iron 

 or its compounds. Occur, 1, native, mono- 

 metric, sp. gr. 7*3-7'8, H. = 4*5, ductile, mag- 

 netic, rarely in veins, more frequently in 

 masses of meteoric origin on the surface ; 2, 

 as Sulphuret, 1, Cubic-Pyrites, monometric, 

 cubical, sp. gr. 4*8-5, H. = 6-6*5, bronze-yel- 

 low, brittle, strikes fire with steel, in rocks of 

 all ages ; 2, White iron-pyrites, trimetric, in 

 tabular crystals, sp. gr. 4*6-4*8, H. = 6-6*5, 

 pale-yellow, brittle, in coal formations ; 3, 

 Magnetic-pyrites, hexagonal, sp. gr. 4*4-4*7, 

 H. = 3*5-4*5, reddish-bronze, brittle, magnetic, 

 in fissures of crystalline rocks ; 3, as Arse- 

 niuret or " Arsenical-pyrites/' in rhombic 

 prisms, sp. gr. 6*1, H. = 5*5-6, metallic, white, 

 brittle, in crystalline rocks ; 4, as Oxide, 1, 

 Peroxide, "Specular-Iron" or " Red-Haema- 

 tite/' rhombohedral, sp. gr. 4*5-5*3, H. = 5*5- 

 6*5, metallic or earthy, steel-gray or red, in 

 crystalline or secondary rocks ; 2, Hydrous- 

 peroxide or " Brown-Hsematite/' stalactitic 

 and botryoidal,or mammillary, or massive and 

 earthy, sp.gr. 3*6-4, H. = 5-5*5, sub-metallic 



