OCTAHEDRAL. 



OcTAHEDEAL Alum Salt, Mohs. Native 

 Alum. See Potash Ai.um. 



Octahedral Ammoniac Salt, Mohs. 

 See Sal Ammoniac. 



Octahedral Arseniate of Copper. 

 Phillips. See Liroconite. 



Octahedral Arsenic Acid, Mohs. See 

 Arsenolite. 



Octahedral Bismuth, 3Iohs. See Na- 

 tive Bismuth. 



Octahedral Chrome Ore, Mohs. See 

 Chromic Iron. 



Octahedral Cobalt Pyrites, Mohs. 

 See Smaltine. 



Octahedral Copper, Mohs. See Na- 

 tive Copper. 



Octahedral Copper Ore, Mohs. See 

 Eed Copper, 



Octahedral Copper Pyrites, Mohs. 

 See Erubescite. 



Octahedral Corundum, Mohs. See 

 Automalite. 



Octahedral Diamond, Mohs. See Dia- 

 mond. 



Octahedral Fluor Haloid, Mohs. 

 See Fluor. 



Octahedral Iron, Mohs. See Native 

 Iron. 



Octahedral Iron Ore, Mohs. See 

 Magnetite. 



Octahedral Kouphone Spar, Hai- 

 dinger. See Sarcolite. 



Octahedral Palladium, Haidinger. 

 See Native Palladium. 



Octahedral Titanium Ore, 3Iohs. See 

 Pyrochlore. 



OcuLUS MuNDi, Kirwan, A hydro- 

 phanous variety of Chalcedony. See Hy- 



DROPHANE. 



OcuLus Piscis, or Fish-eye Stone. See 



ICHTHYOPHTHALMITE. 



Odontolite, or Bone Turquois. Fossil 

 or teeth coloured by oxide of copper, 

 found in Europe, in Bas Languedoc. The 

 word is derived from <5So?, a tooth, and >^'(los, 

 a stone. See Turquois. 



CErstedite ; (Erstedtit, Kenngott. 

 Probably an altered Zircon. 'Colour reddish- 

 brown Lustre adamantine-vitreous. Opaque, 

 or subtranslucent. H. 5-5. S.G. 3-629. 

 Analysis, by Forchammer : 



Zirconia and titanic acid . 68 96 

 Silica ..... 19-71 

 Lime . . . . . 2-61 

 Magnesia .... 2-05 

 Protoxide of iron . , . 1-14 

 Water 6-53 



100-00 



OIL COAL. 263 



BB infusible ; with borax or microcosmic 

 salt yields a colourless glass. 



Locality. Arendal, in Norway, in bril- 

 liant crystals, generally on crystals of 

 Pyroxene. 



Name. After J. C. CErsted, the Swedish 

 chemist. 

 Brit. Mus., Case 37. 



Ogcoite, Breithaupt. A variety of Eipi- 

 dolite, from Kauris, in Upper Austria. S.G. 

 2-9. 



Analysis, by v. Kobell : 



Silica 26-06 



Alumina .... 18-47 

 Magnesia .... 14*69 

 Protoxide of iron . . . 26-87 

 Protoxide of manganese . 0-62 

 Water . . ". . . 10-45 

 Gangue .... 2-24 



99-40 

 Name. From oyAa, to increase in hulk ; in 

 allusion to its behaviour before the blow- 

 pipe. 



Oil Coal. A kind of Coal occurring 

 under bituminous coal, and affording a large 

 quantity of oil on distillation. It varies in 

 colour from brown to black, and is dull 

 when not exhibiting the polished appear- 

 ance of " slickenside." Powder dark choco- 

 late colour. Very tough. Fracture hackly. 

 S.G. 1-103. 

 Analyses, by Slessor: 



Volatile matters . . . 66-56 

 Fixed carbon . . . 25-33 

 Ash 8-21 



100-00 



Carbon . , . .80-96 



Hydrogen .... 10*15 

 Nitrogen with oxygen and 



sulphur .... 0-68 

 Ash 8-21 



100-00 

 It takes fire very readily, and when re- 

 moved from the lamp still burns for some 

 time with a brilliant smoky flame, and while 

 flaming melted fragments continue to drop 

 from it in a highly characteristic manner. 



Locality. This coal occurs in the Coal- 

 measures of Nova Scotia, at Fraser Mine, 

 near Pictou, in a bed from 14 inches to 

 20 inches thick, under bituminous coal. 

 Throughout its entire thickness, it has a 

 curh' twisted structure, and many of its 

 fractures look like the casts of shells, and 

 the sharp edges have the polished character 

 of slickensides. 



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