MINERALOGY. 



vood-hrown, and from its fibrous flruflurc it prcfents the 

 rcfcmblance of wood. 



AsBEsTous jlalnolite. See Sthahlsteix. 

 AsBEsrovfi Tremo/ite. See Thkmolite. 

 Aspauagus-Stone. See Apatite, AdcJemla. 

 Asi'iiALT, flag mineral pitch ; Bitume follde, Haiiy. 

 (See Am'iialtu-M.) Afphalt appears to be indurated 

 petroleum : it occurs in veins, interfering ftrata connefted 

 with coal (Irata, and near bafaltic rocks. 



Atacamite, muriate of copper. See Coppeu-Okes, 

 and Sandy Copper. 



AuGlTE, Pyroxene, Haiiy. (SeeAL'GlT.) Since that 

 article was written, it has been difcovered that augite forms 

 a conftituent part of many bafaltic rocks in Great Britain, 

 and that it is alfo a common conftituent of almoft all dark- 

 coloured lava. (^SeeVoLCA'Sic Produds.) Augite occurs 

 cryftallized, and in angular and round pieces. The cryftals 

 are generally lix or eight fided prifms, with dihedral fum- 

 mits. According to Haiiy, the primitive form is an oblique 

 rhomboidal prifm, the alternate angles of which are 92° 1 8' 

 and 87° 42'. The colour of augite inclines to green and 

 greenifh-black : it is more or lefs tranflucent. Augite has 

 generally a darker colour than olivine, and a greater hardnefs 

 and f])ecific gravity. They very frequently occur together 

 in bafalt and lava. Werner divides augite into four fub- 

 fpeoics : granular augite, which is opaque, and has hitherto 

 been found only at Arendal in Norway : foliated augite, the 

 luftrc of which is refino-vitreous and internally fliining, ap- 

 proaching to fplendent ; it occurs at Etna and Vefuvius, and in 

 the bafalt of Bohemia : conchoidal augite, which is fometimcs of 

 an olive -green colour, and has an imperfect flat conchoidal 

 fracture : and common augite. There is alfo a variety of augite 

 ■which occurs maflTive or difleminated, of a deep black colour 

 and opaque ; this has been called77fl'^^_y augite. The term py- 

 roxene, or a ttranger to fire, given to this mineral by Haiiy, 

 is extremely inappropriate, as this mineral forms a conftituent 

 part of moft dark-coloured lava. 



Automalite, Spinelle %incifere, Haiiy. (See Ruby.) 

 This mineral is clafied with the fpinel-ruby. The fpecific 

 gravity is from 4 to 4.2 : it is remarkable for containing 28 

 fer cent, of oxyd of zinc. It occurs imbedded in talcous 

 flate at Fahlun, in Sweden. 



Axinite. See Thummerstone. 

 Azure-Stone, Laxulite, Haiiy. See Lazuli Lapis. 

 Basalt. See Basalt, Addenda, and Whin-stoxe, 

 RowLEY-i?r7^, and Volcanic ProduBs. 



Basaltic Hornblende, Ampbibole cryjlallizee, Haiiy. 

 This mineral is frequently confounded with fchorl by the 

 older mineralogifts : it has a velvet -black or brownifli- 

 black colour ; it occurs in irregular fix-fided prifms, va- 

 rioufly acuminated, but moft frequently by flat trihedral 

 pyramids with rhomboidal faces. The ftrufture is lamellar, 

 •with joints m two direftions parallel to the fides of an 

 oblique rhomboidal prifm, the alternate angles of which 

 are 1 24^° and 55!°. It is opaque, and has a fplendent 

 and vitreous luftre ; it has a fine-grained uneven frafture ; 

 it fcratches glafs ;_ and melts with difficulty into a black 

 glafs. The fpecific gravity is from 3.15 to 3.25. The 

 conftituent parts, as given by Klaproth, are 



Silex " - - . . ^^^ 



Alumine - - - - 26 



Lime - - . . g 



Magnefia - - - . 2 



Oxyd of iron - - - ir 



Water - - . .^q 



98.50 



It occurs in common bafalt, in wackc, and in lava ; alfo 

 in fome kinds of porphyry. It decompofes more flowly 

 than bafalt ; hence, according to profeftbr Jamcfon, we 

 frequently find cryftals of bafaltic hornblende difperfed 

 through clay formed by the decompofition of bafaltic 

 rocks. See Hornblende, Addenda. 



Basanite, black flinty flate. See Slate. 



Bergmannite, a mineral which occurs maflive with 

 grey and red quartz at Freidichfwarn, in Norway, and is 

 clafled with fcapolite in the felfpar family in Jamefon's 

 Mineralogy. Its colours are greenifti and greyifli-white, 

 or yellowifli-grey and muddy flefli-red. It is extremely 

 gliftening, with a luftre betw-een pearly and refinous. The 

 ftrufture is delicately fibrous, curved, or diverging. It is 

 faintly tranflucent on the edges, and fcratches felfpar. It 

 melts before the blow-pipe without intumefcing into a 

 white enamel. 



Beryl. (See Beryl and Emerald.) In Weifs's col- 

 leftion at Vienna, there are two cryftals of beryl in a group 

 crofling each other, which are a foot and a half in length, 

 and one foot in diameter. It has been found in alluvial 

 foil, in the upper part of Aberdeenfliire, and in the county 

 of Wicklow, in Ireland, imbedded in granite. 



BiLDSTEiN. See Agalmatolite. 



Bismuth, Native. See Bismuth-0/y. 



Bismuth, Glance, or Sulphuretted Bifmuth. See Bis- 

 muth-O/v. 



BiSMUTH-Orf , Plumbo cupriferous, has a fteel-grey colour, 

 with a pale copper-red tarnifli. It occurs difl^eminated and 

 cryftallized in oblique four or fix-fided acicular prifms, lon- 

 gitudinally ftreaked. The cryftals are frequently adhering 

 together, and are fometimes curved, and divided by crofs 

 rents. The luftre is metallic. The crofs fradlure is fine- 

 grained and uneven. It yields eafily to the knife. The 

 fpecific gravity is 6.2. Before the blovv-pipe, it melts into 

 a fteel-grey globule ; by continuing the heat, it is partly 

 volatilized, and depofits in the charcoal a yellow powder, 

 after which there remains a red globule, containing a grain 

 of cupriferous metallic lead, which communicates a blueifli- 

 green colour to borax. According to John, the con- 

 ftituent parts are. 



Bifmuth 



Lead 



Sulphur 



Sulphur 



Nickel 



Tellurium ? 



Gold 



43.20 



24.32 



12.10 



11.58 



1.58 



1.32 



0.79 



94.89 



It occurs near Berezof, in the diftrift of Catharinen- 

 burg, in Siberia. 



BlNMUTii-Orc, Cupreous, or Cupriferous fulphuretted Bif- 

 muth-Ore, has a light lead-grey colour, fometimes fteel-grey 

 and tin-white. It occurs maflive, diffeminated, and in 

 diverging prifms. The luftre is metallic ; it is fedtile. 

 According to Klaproth, the conftituent parts are, 



Bifmuth - - . - 47.24 



Copper .... 34-66 



Sulphur .... 12.58 



94.48 



This is a very fcarce ore of bifmuth. 



BisMUTHic Sil-ver-Ore. See Silver-Ore. 



Bitumen, 



