CORUNDUM. 



frequently with the Corundum of Asia 

 Minor. 



Name. From Corund (^Corundum), and 

 ft^og, a fritnd. 



Brit. "Mus , Case 32. 



Corundum, Phillips. Corundum-stone. 

 Hexagonal : commonly occurs crystallized 

 in six-sided prisms, which rarely exhibit a 

 tendency to iiat triednd terminations ; also 

 in obtuse and acute hexahedral pyramids. 

 It is likewise found granular or compact. 

 Sometimes nearly colourless and slightly 

 translucent, but more frequently with a 

 greyish, greenish or reddish tint, or brown 

 with a chatoyant lustre. Fracture con- 

 choidal, uneven. Extremely tough when 

 compact. H. 9. S.G. 39 to 4-1, 



Fig. 132. 



Fig. 133. 



Comp. ^1 or oxide of aluminium, when 

 pure. — Aluminium o3-19, oxygen 46-81 = 

 100-00. ' 



Analysis oi Corundum of India, by J. 

 Lawrence Smith : 



Alumina 

 Magnesia 

 Lime . 

 Silica . 

 Water . 



9^-12 

 091 

 1-02 

 0-96 

 2-86 



98-87 



BB like sapphire. 



Localities. In hexagonal crystals at 

 Carrock Fells in Cumberland, and' in small 

 rolled fragments in the bed of a stream in 

 the county of Wicklow. Foreign.— In 

 granite rocks in China, Aya, on the coast of 

 Malabar and in the Carnatic : also less 

 abundantly at Gellivara, in Sweden, in 

 Magnetic Iron ; near Mozzo in Piedmont, 

 and at St. Gotthard Largely in Asia Minon 



Name. From the Indian, Korund. 



This is the hardest of all known bodies, 

 except the Diamond. The name Corimdum 

 is commonly confined to the opaque rough 

 crystals and cleaveable masses, generally of 

 dingy colours and often dark ; while "the 

 term Emerj' embraces the more or less im- 



COUZERANITE. 97 



pure, massive, granular and compact kinds, 

 and Sapphire and Ruby comprise the 

 transparent, brightly- tinted varieties. 



It is used extensively for polishing steel 

 and cutting gems. See Emery. 



Brit. Mus, Case 19. 



31. P. G. Horse-shoe Case, Nos. 783 to 

 785; Wall-case 41. 



CoTHAM, Ruin, or Landscape Marble. 

 A liglit grey argillaceous limestone, occur- 

 ring in thm inegular layers, from two to 

 six inches thick, at Cotham and other 

 places in the neighbourhood of Bristol. 

 Slices of the stone cut at right angles to the 

 bedding exhibit, when polished, fanciful 

 representations of landscapes, and ruins, 

 which have caused it to be called, also, 

 Ruin or landscape marhle. 



According to Charles Moore this stone 

 forms the lowest bed of the "White Lias "' 

 at Pyile Hill, on the Bristol and Exeter 

 Railway, near Bristol. It is also stated by 

 Phillips to be of common occurrence in the 

 Val d'Arno, near Fjorence. 



CoTTONSTONE. The name given to Me- 

 solite in Skye. 



CoTDNNiA, Monticelli §• Covelli. CoTUN- 

 NITE, V. Kobell. Rhombic. In extremely 

 minute, white acicular crystals, with an 

 adamantine lustre inclining to silky or 

 pearly. Streak white. May be scratched 

 with "the nail. S.G. 5-23. 



Comp. Chloride of lead, or Pb CI = lead 

 74-5 chlorine 25-5 = 100-0. 



BB fuses easily, colouring the flame blue, 

 and emitting a white smoke which is con- 

 densed on the charcoal. With soda yields 

 a globule of lead. 



Soluble in about twenty-seven times its 

 weight of cold water. 



Locality. This mineral was observed by 

 Monticelli and Covelli, in the higher crater 

 of Vesuvius, after the ei-uption of 1822 ; 

 next in 1840, soon after the eruption of 

 1839, in the upper crater, near the Punta 

 del Mau'O; and lately in the lava of 1855, 

 which ran into the Fosso della Vetrana. 



Name. After a medical man in Naples. 



Brit. INIus., Case 59. 



3I.P. G. Upper Gallery, Table-case A, in 

 recess 4, No. 148. 



CouPKRosE Blanche. See Goslarite. 



CouPKKosE Blkue. See Cyanose. 



CouPEROSE Jaune. See Copiapite. 



CuuFKROsE Vertk. See Copperas. 



Couzekamte, Charpentier. Occurs in 

 small, but perfect, square prisms imbedded 

 in limestone. Colour greyish-black to 

 indigo-blue. Lustre vitreous or resinous. 

 Opaque, but in fragments transparent and 



