NICKEL AND COBALT. 445 



A carbonate of iron, called chalybite, or spathic ironstone, is very abun- 

 dant in nature, and forms obtuse rhombohedrons. It is very useful for the 

 production of steel, as it forms the clay iron ore found in coal districts in 

 combination. In a fibrous form it is known as sphcerosiderite. It is a most 

 useful mineral. 



Chrome iron (chromite) is useful for the preparation of chromium 

 compounds. It crystallizes in the cubic system. It is magnetic, especially 

 when treated. Chromic acid forms scarlet " needle" crystals, and by its 

 assistance chromate of lead, or chrome yellow, is prepared. (Chromate of lead 

 is found in a native state as crocoisite). See Chromium. 



MANGANESE is contained in several minerals. It usually occurs as an 

 oxide. It colours minerals variously. In a pure state manganese is white 

 and brittle. The chief minerals are 



Pyrolusits (the binoxide of manganese of commerce) occurs in crystals. It 

 is black. It is used in the preparation of chlorine and oxygen. The other 

 minerals are known as manganite, which is also found associated with pyro- 

 lusite, as are hausmannite and brannite, the other oxides. 



NICKEL and COBALT are generally found together, both being similar, 

 and the minerals are compounds of arsenic or sulphur, and occur under 

 similar circumstances. The principal are of NICKEL and of COBALT 



Sulphide of nickel (ullmanite). Arsenical cobalt (smaltine). 



Arsenical nickel (nickeline). Cobalt glance (cobaltine). 



Nickel glance (gersdorffite). Cobalt bloom (erythrinej. 



Nickel pyrites (siegenite). Cobalt pyrites (linnaeite). 



Nickel ores are used for extraction of the metal, which is used as a 

 substitute for silver. The name is derived from the German, kupfernickel y 

 or false copper. It was discovered in 1/51. 



COPPER, again, forms a number of minerals, and the chief is the red 

 oxide of the metal, called cuprite. It crystallizes in the cubic system. Its 

 colour is red, and tinges a flame green. Ctiprite yields excellent copper, 

 and is found in Cornwall, and in many places on the continent. The black 

 oxide is rarely found. It is known as melaconite. 



Malachite (carbonate of copper) is remarkable for its beautiful green 

 colour. In Australia it is worked for copper. It is chiefly ornamental. 

 Siberia yields the finest specimens, but the mineral is found in Cornwall and 

 Cumberland, as well as on the continent. Chessylite (from Chessy, in France) 

 is frequently found with malachite. It has been called blue malachite, or 

 the azure copper ore. It is used as a paint. 



Besides the above, copper unites with sulphur to form minerals, such as 

 the needle ore (bismuthic sulphide of copper), antimonial sulphide, bourno- 

 nite ; purple copper, and copper pyrites, which is very abundant, and 



