264 OISANITE. 



Oil-coal yields from 40 to 77 gallons of 

 crude oil per ton on distillation, and in picked 

 samples as much as 179 gallons. 



All the Oil Coals have a greater density 

 than ordinary coals, and the volatile matters 

 they contain are greatly in excess of the 

 carbon ; while in all the bituminous coals, 

 and in a few cases in Cannel Coals, the vola- 

 tile matters are considerably less in amount 

 than the iixed carbon. 



OisANiTE, A name for Anatase, from its 

 principal locality, Bourg d'Oisans, in Dau- 

 phin e. 



Okenite, v. Kohell. Generally occurs in 

 delicately fibrous and sometimes in radi- 

 ating masses. Colour snow-white, with a 

 tinge of yellow or blue. Lustre glimmering 

 or pearly, often opalescent. Translucent at 

 the edges. Very tough. H. 5. S.G. 2-28. 



Comp. Hydrated bisilicate of lime, or 



Ca Si2 + 2H = lime 28, silica 62, water 18 = 



100. 



Analysis, by v. Kohell : 



Silica 55 "64 



Lime 26-59 



Alumina and peroxide of iron 0-53 



99-76 



BB swells up, and fuses to a porcelain - 

 like mass; with borax yields a colourless 

 globule. 



When pulverised, easily dissolved in cold 

 muriatic acid (but not after ignition), with 

 separation of gelatinous flakes of silica. 



Localities. Disco Island and Tupaursak, 

 in North Greenland, in amygdaloid. Faroe, 

 Iceland. 



Name. After Professor Oken, of Munich. 



Brit. Mus., (:!ase 28. 



Oligiste, Haiiy. (From oxtyiffm^ least, 

 signifying that it is less rich in metal than 

 Magnetite.) See Specular Ikon. 



Oligoclase. Anorthic: crystals rather 

 rare, twins common, and resem'bling Albite. 

 Cleavage perfect. Colour white, with a tinge 

 of grey, green, yellow, pr red. Lustre pearly 

 or resinous on the cleavage planes; else- 

 where vitreous. More or less translucent. 

 Fracture conchoidal or uneven. H. 6. S G 

 2-58 to 2-7. 



Comp. 35faSi + 4(Ai Si3) = silica 62-3, 



alumina 23-5, soda 14-2 = 100. 



■ Analysis, from Teneriffe, by Deville ; 



Silica . . . . . 62 97 



Alumina .... 22-29 



Lime ..... 2-06 



sia . . . . 0-54 



OLIVENERZ. 



Soda 8-45 



Potash .... 3-69 



100-00 



BB like Felspar, but fuses with much 

 greater ease to a transparent, colourless 

 glass. Not decomposed by acids. 



Localities. Teneriffe, in trachyte. With 

 Quartz and Mica forming granite at Kimito 

 in Danvikszoll near Stockholm. Schaitansk 

 and Lake Baikal, in Siberia. Iceland. 

 Arendal, in Norway. Arrifege. Morea. Had- 

 dam, Connecticut, &c. U. S. 



Name. From «A/j/o?, little, and xXkoj, to 

 break. 



Brit. Mus., Case 30. 



For varieties of Oligoclase, see Hafnef- 

 joRDiTE, Moonstone, Sunstone, Unio- 



NITE. 



Oligoclase-albite. The name pro- 

 posed by Scheerer, for an Albite from Sna~ 

 rum. 



Oligon Spar, Oligonspath, Breithanpt. 

 A variety of Spathic Iron from Ehrenfried- 

 ersdorf, in Saxony, containing 25 per cent, 

 of protoxide of manganese. Occurs in rhoni- 

 bohedrons. Colour reddish-yellow. H. 4. 

 S.G. 3-74. 



Comp. 2MnC + 3FeC. 



Analysis, by Magnus : 

 Carbonic acid . . , 38-35 

 Protoxide of iron . .36-81 



Protoxide of manganese . 25-31 



100-47 

 Olive Copper Ore, Kirwan. See Oli- 



VENITE. 



Olive Malachite, Mohs. See Olive- 



NITE. 



Olivenchalcit. See Libethenite. 



Olivenekz, Werner Olivenite, Beu- 

 dant. Olivenit, Haidinger, Leonhard. 

 Olivenite, Dana, Greg §■ Lettsom. Oli- 

 ven-ore, Jameson. Rhombic : primar}' 

 form a right rhombic prism. Occurs ,in 

 prismatic crystals, which are usually at- 

 tached to the matrix : also reniform, fibrous, 

 and capillaiy, and granular. Colour^ olive- 

 green, pistachio-green, and blackish-green. 



Fig. 314. 



passing into liver-brown and wood-brown ; 

 the fibrous variety ( Wood-arseniate) sisldn- 



