MINERALOGY. 



Bitumen, Liquid, Tenacious, Sola], Compa&, and Elajlic. 

 See Bitumen. 



Bituminous Marh-Slate occurs in beds in the lower 

 llratified lime-ftone in various parts of Europe. It has a 

 dark-brown or blackidi-grey colour, a glimmering or glif- 

 tening luftre, a flaty ftruclure, and is foft, meagre, opaque, 

 and feclile. It frequently contains ores of copper. It is 

 remarkable for the number of petrified fi(h which occur in 

 it. It alfo contains foflil remains of (hells, corals, and of 

 cryptogamous freili-water plants. In many of its characters, 

 it appears to refemble the alum-fliale of Whitby. It is 

 a frequent mineral in Saxony, Thuringia, Franconia, Bo- 

 hemia, Bavaria, and in Switzerland. 



Bituminous Wood, a variety of brown-coal or wood- 

 coal, in which the fibres of the wood are diftinguifhable. 

 See Coal and WooD-Coa/. 



Black Coal. See Coal. 



Black Chalh, or Draiving-Slate, Ampelite graphique, Fr. 

 occurs in beds, in rocks of the flate formation. It has a 

 blueifli or greyilh-black colour, a flaty ftrudure, an earthy 

 crofs fraCfure, is dull, meagre to the touch, and leaves a 

 diftinft mark on paper. It is fettile, and becomes gliilen- 

 ing in the ftreak. The fpecific gravity is 2.1 1. Accord- 

 ing to Wregleb, its conftituent parts are. 



Boracite, Magnefii boratte, Hauy. (See Boracite.) 

 Vauquehn found no lime in this mineral, and fuppofes it 

 to be a fimple borate of magnefia. Boracite is remarkable 

 for its eleftric properties when heated. The form is gene- 

 rally that of tlie cube, and thofe angles which are diagonally 

 oppofite are, one pofitive, and the other negative, forming 

 eight eleftric poles. 



Botryolite occurs in mamillary or botryoidal concre- 

 tions, in a bed of gneifs, near Arendal in Norway, afib- 

 ciated with quartz, fchorl, calcareous fpar, and iron pyrites. 

 Its colours are, pearl-grey, greyifh or reddirti-white, and pale 

 rofe-red. The colours are concentric ftripes. It has a delicately 

 fibrous ftellular ftrufture, and fometimes a fpUntery fracture. 

 It has a pearly gUramering luilre internally, is tranflucent 

 on the edges. According to Klaproth, the fpecific gravity- 

 is 2.88 ; and the conftituent parts are, 



Silex 36.0 



Lime - - . . . 3c). 5 

 Boracic acid - - - - i3-5 

 Oxydofiron - - - - i.o 

 Water - - - - - - 6.5 



Silex 



Alumine - 

 Carbon 

 Water 

 Iron - 



64 

 1 1 

 1 1 



7 

 3 



It is found at Morilla in Spain, in Brittany, in Germany, 

 and in Italy. It is cut into fquare pencils, and ufed for 

 drawing ; it is alfo ground and ufed in painting. Thofe 

 varieties which have the darkeil colour and the fineft earthy 

 texture are to be preferred. The pencils become hard, 

 unlefs kept in a moill place. 



Black-Jack, a provincial name for blende. 



Blende, Black, Broivn, and Telloiv, various fulphurets 

 of zinc. See Zinc-Ores. 



Bog Iron-Ores. (See Iron-Ores. ) Werner fuppofes 

 bog-iron, whether in meadows, fwamps, or marrties, to be 

 formed by water impregnated with vegetable acid, dif- 

 folving part of the iron in the rocks over which it flows, 

 which, being poured into hollows, becomes ilagnant, and 

 evaporates. Thus fucceflive depofitions are formed, which 

 are at firfl yellowifli earthy, and of little confiftence. This 

 is morafs-ore. In courfe of time, it becomes harder, and 

 the colour pafles to brown, forming fwamp-ore. After 

 the fwamp is dried up, the ore becomes much harder, and 

 pafles into meadow-ore, which is covered with foil and 

 vegetation. 



Bole. See Bole. 



BoLOGNESE Spar, or Radiated Heavy Spar. See 

 Heavy Spar, ylddenda. 



Boracic Jlcid, Native or Sajfoline, is found in faline 

 incruftations on the borders of hot fprings, near Saflb, in 

 the territory of Florence. It has a greyifh or yellowilh-white 

 colour ; it occurs in thin crufts or minute pearly fcales ; 

 it is foft and friable, and is feebly tranflucent. To the tafte, 

 it is flightly bitter and acidulous. It melts eafily before 

 the blow-pipe into a tranfparent globule. According to 

 Klaproth, the conftituent parts are, 



Boracic acid - - - - 86 

 Ferruginous fulphate of magnefia 1 1 

 Sulphate of lime ... 3 



100 



96. 



Earthy botryolite occurs with the above, which has a 

 fnow-white colour, and an earthy frafture. 



BovEY Coal. Bituminous wood coal, found at Bovey 

 Heathfield, Devonfliire. See Coal. 



Broxzite, Diallage metalloide, Haliy. A mineral 

 nearly allied to Labrador hornblende or hyperftene. It has 

 a yellowilh-brown or pinchbeck-yellow colour, and a femi- 

 metaUic luftre : it occurs malTive, and coarfely difleminated : it 

 has a foliated and fibrous ftrufture, with a diftinft fingle 

 cleavage. It is opaque. The fpecific gravity is 3.2. 

 According to Klaproth, the conftituent parts are, 



Silex 

 Magnefia 

 Iron 

 Water - 



60.0 



27.5 



10.5 



0.5 



98.5 



It occurs in fienite at Glentilt, in Perthfliire, and at the 

 Lizard, in Cornwall, intermixed with jade in ferpentine. 



Brown Spar, Pearl Spar, or Dolomite Spar ; Chaux car- 

 lonatee ferro manganefefere, Haiiy ; Bitter Spath, Werner. Its 

 prevailing colours are, milk-white, greyilh-white, yellowilh- 

 grey, and pearl-grey : it alfo occurs red, brown, yellow, and 

 black. It occurs both maflive and cryftallized in obhque 

 rhomboids, and in comprefled hexahedrons. The joints are 

 parallel to the faces of an oblique rhomboid, the alternate 

 angles of which meafure 106° 18' and 73° 45'. The faces 

 of the rhomb are fometimes convex or concave ; it occurs 

 alfo in lenticular forms. The luftre is fhining, and between 

 vitreous and pearly : it is more or lefs tranflucent. It yields 

 to the knife, but is harder than calcareous fpar. Its ipeeific 

 gravity is from 2.1S to 2.88. It hardens and becomes an 

 opaque brownifli-black before the blow-pipe. It diflblves 

 flowly in cold muriatic acid, but with confiderable effer- 

 vefcence in hot acid. According to Klaproth, the con- 

 ftituent parts are. 



Carbonate of lime 



magnefia 



Oxyd of iron and manganefe 



4A 2 



- 53 



- 43 



- 3 



99 



The 



