HEMATITE 533 



HAEMATITE. 



Haematite is an opaque mineral with a metallic lustre and dark steel-grey to iron- 

 black colour. Chemically it consists of ferrous oxide, FcgOg, and in its purest form 

 contains 70"0 per cent, of iron and 30'0 per cent, of oxygen. Specially fine rhombohedral 

 crystals occur not infrequently in the extensive and important deposits of iron-ore in the 

 island of Elba, and in veins and crevices in the gneiss of the Alps, and at other places. Only 

 those of some thickness are black and opaque, and exhibit a brilliant metallic lustre ; minute 

 crystals of extreme thinness appear by transmitted light transparent and of a fine blood-red 

 colour, hence the Greek name hematite (blood-stone). The streak of this mineral on 

 unglazed porcelain is dull and of a dark cherry-red colour, a feature which distinguishes it 

 from all other black stones possessing a metallic lustre. 



Haematite occurs more abundantly than in crystals as compact irregular masses of a 

 black colour, with a shining metallic lustre, and with the same specific gravity (sp. gr. = 4"7) 

 and the same hardness, namely, that of felspar (H= 6), as the crystals possess. The 

 latter are scarcely ever cut, but the massive material is worked in the lapidary works at 

 Oberstein and elsewhere for the manufacture of ornamental objects. The material used for 

 this purpose, which is obtained in masses of considerable size, is said to come from India, 

 and similar material occurs also in Brazil, in the States of Sao Paulo and Minas Geraes. 



Finely fibrous haematite, the application of which is perhaps still more extensive, doe.s 

 not, as a rule, possess the brilliant metallic lustre of the crystals and of the compact 

 crystalline masses just mentioned, and its colour is reddish and more like that of the streak. 

 Specimens are sometimes met with, however, which, while retaining their fibrous structui-e 

 possess a brilliant metallic lustre and a steel-grey to black colour. Material of this description 

 is as suitable for cutting as the crystalline masses described above, but fibrous haematite 

 when distinctly red in colour is useful only as an ore of iron. The latter variety usually 

 occurs in rounded, botryoidal, or reniform masses and is then known as kidney-iron-ore ; 

 this occurs lining cavities in massive haematite of a pronounced red colour. Haematite of 

 this character suitable for cutting was at one time obtained in the veins of iron-ore at 

 Kamsdorf, near Saalfeld, in Thuringia, but these deposits are now practically exhausted ; 

 also in the famous old iron-mines in the island of Elba, where magnificent druses of 

 beautiful crystals are often found. Material suitable for cutting is found also in the deposits 

 of iron-ore in Scotland, and in the iron-mines of west Cumberland, but the most important 

 occurrence is in the iron-mines of the north of Spain, near Bilbao, in the Basque Provinces, 

 and at Santiago de Compostela in Coruna. Rough material of suitable quality for cutting is 

 found also at many other localities beside those enumerated above. 



The deeper the black colour and the more perfect the metallic lustre of haematite the 

 more effective is it for the various ornamental purposes to which it is applied. For ring- 

 stones it is cut with a flat surface, on which is engraved a figure or a letter, so that it may 

 serve as a seal-stone, and this is one of its most general uses. Stones cut en cabochon for 

 rings and other articles of personal ornament sometimes display a band of chatoyant light, 

 wliich, though cloudy and dull, is similar to the characteristic feature of star-sapphire, and 



