COLLKCri K^NS IN ECONOMIC (JEOLOGY AND METALLURGY. 113 



the mineral. To illiistiate the occiineuce of hematite live si)ecimeus 

 are shown : 



(1) Tabular crystals, on massive. Iron Kidge, Crawford Couuty, Missouri. 

 (40729.) 



(2) Specular. Lake Superior Mine, Ishpeniiug, Mar(|nettc County, Michigan. 

 (5358.) 



(*3) Micaceous specular. Negaunee, Marquette County, Michigan. (.'):W5.) 



(4) Massive. Athens, McMinn County, Tennessee. (20068.) 



(5) Fossiliferous. Ferguson Valley, Lewistou, Pennsylvania. (51815.) 



LIMONITE. (BROWN HEMATITE, BOG IRON ORE.) 



Composition: Fe^Os + Fe^HfiOg. Hydrated sesquioxide of iron, con- 

 taining sesquioxide of iron 85.6 per cent, (iron, 59.9 per cent.), and 

 water 14.4 per cent. 



It does not crystallize, but is generally found in various imitative 

 shapes with fibrous structure, frequently coating the interior of cavities. 

 It also occurs massive. It varies in hardness from 5 to 5.5, and in 

 specific gravity from 3.6 to 4. The luster on the original surface is often 

 bright metallic, and dark in color, while on a fresh fracture the luster 

 is generally silky, and the color brown; occasionally it occurs earthy. 

 The powdered material is always yellowish brown. 



Limonite is the most widely distributed ore of iron, and as the metal 

 is very easily reduced from it, has been utilized in remote and inacces- 

 sible regions for long ages. The purer varieties yield a metal of great 

 strength, well suited for making castings, and especially car wheels. 

 To illustrate the occurrence of limonite two sj)ecimens are shown : 



(1) Botryoidal and stalactitic, fibrous coating on the interior of cavity. Chatfield 

 Mine, Salisbury, Litchfield County, Conuecticut. (17302.) 



(2) Massive. Mine No. 1, Lownioor, Alleghany County, Virginia. (5301.) 



TURGITE. 



Composition: 5 Fe203+Fe2H606 Hydrated sesquioxide of iron, con- 

 taining sesquioxide of iron 94.7 per cent, (iron, 00.3 per cent.), and 

 water 5.3 per cent. 



Does not cr^'stallize, but resembles limonite, with which it is gen- 

 erally associated in its occurrences and physical properties, but from 

 which it can most readilly be distinguished by its powder being red. 



To illustrate the occurrence of turgite two specimens are shown : 



(1) Coating the interior of a cavity on limonite. Porter Ore Hod, Salisbury, 

 Litchfield Couuty, Connecticut. (11(JU4.) 



(2) Po\vder(!d sample, showiug characteristic red color. Porter Ore Hed, Salis- 

 bury, Litchfield County, Conuecticut. (65321.) 



SIDERITE. (SPATHIC IRON.) 



Composition: FeCOa. Carbonate of protoxide of iron, (u)ntaining 

 protoxide of iron 62.1 per cent, (iron, 4!).(> per cent.), and carbonic acid 

 37.9 per (!ent. Generally a i)art of the iron is replaced by manganese. 

 9110— No. 42 6 



