MINERALOGY. 



lamella.- ftrufture is nearly loft in many of the compad fel- 

 fpars, particularly i.. thofe varieties which have httle lullre. 

 When it contains cryftals of quartz or felfpar, ,t conib utes 

 a felfpar porphyry. It forms extenfive beds ,n many alpme 

 diftrias. It is diftinguilhed from horn-ftone by its inferior 

 hardnefs, fuf.bility, and its frequent intermixture with horn- 

 blende or mica. .„ ,. . 



DifuUe^rnted Felfpar has general y a greyiHi-white colour. 

 It occurs maffive and in imbedded cryihils which have the 

 fame form as common felfpar. It is gliftemng, glimmering, 

 or dull, and foft and fec^ile. In fome inftances, it appears 

 to be felfpar in a decompofing ftate ; in others, to be a loiter 

 kind of felfpar in an unaltered ftate. 



FiBROLiTE, a mineral which occurs with corundum ; it 

 has a white or grey colour, is cryftallized in rhomboidal 

 prifms, the angle of whofe planes are 80° and 100°. It 

 has a fibrous ilrufture, and an uneven crofs fradure. In- 

 ternally it is ghllening. Fibrolite is harder than quartz. 

 Its fpeciiic gravity is 3.21. According to Chcnevix, the 

 conftituent parts ai-e, 



Alumine 



Silex 



Iron and lofs 



58.25 



38.00 



3-75 



Pigure-Stoxe. Agalmetolite, or bildfteen. 

 FlSH-EYE-5/oni?, or ichthyophthalmite. 

 Flint. See Flint. 



Float-Stone, Qwarz 7ieaique, Haliy ; fometimes 

 called fwimming quartz. Its colours are yellowilh -white 

 and grey. It is didl, earthy, and friable, abforbs water 

 and becomes tranflucent. Its fpecific gravity is lefs than 

 •water, being from 0.448 to 0.793. The conftituent parts 

 are, 



Silex - - - - 91 to 98 

 Water ... 6 



Carbonate of lime - 2 



Oxyd of iron and alumine 2 



It is found at St. Oien, in the vicinity of Paris, along 

 ■with flint, and fometimes contains the fame petrifaftious as 

 thofe found in flint. Flint is fometimes found in the centre 

 of float -ftone, and pafles into it by gradation. Float -ftone 

 may therefore be confidered as a porous ftate of flint. 



Flos Ferri, Coralloldal jirragonlte, occurs in fnow- 

 •white dendritical branches, either fmooth or incrufted with 

 points. It is found in the mines at Dufton Fell, Weft- 

 moreland ; it is fuppofed by count Bournon to be formed 

 by fublimation. 



Fluor Spar, FIus, Werner ; Chaux Jluatee, Fr. See 

 Fluor Spar. 



Foliated Granular Lime-Jlone. The name given by 

 Mr. Jamefon to cryftalline primitive lime-ftone, called by 

 the French chaux carhonatee fauaroide. See LlME-STONE, 

 and Lime-stone, Addenda. 



Fossil-Copal, or Highgate Refin, a refinous fubllance 

 found in perforating the bed of London clay at Highgate. 

 It appears to be a true vegetable gum or refin, partly 

 changed by remaining in the earth. It gives out a refinous 

 aromatic odour when heated, and melts into a limpid fluid. 

 It takes fire when applied to the flame of a candle, and 

 burns away entirely before the blow-pipe. The colour of 

 foflil-copal is a yellowifh-brown : it has a refinous luftre, is 

 brittle, and yields eafily to the knife. The fpeciiic gravity 

 is 1.046. 



Fullers'-Eartii, Argik fmenlque, French. See Ful- 

 lers' -Earth. 



Gadolinite. See Gadolinite. 



Galena, or Sulphuret of Lead, Lead Glauce ; Plomb 

 fulphure, Haiiy. See Lead. 



Garnet, Grenat, French. (See Garnet, Precious, and 

 Garnet, Common.) The garnet family of Werner and pro- 

 fefTor Jamefon, in their mineralogical fyftems, comprifes 

 the following minerals, fuppofed to have an alliance with 

 garnet : leucite, vefuvian, groffalar, melanite, allochroite, 

 garnet, grenatite, pyrope, and cinnamon-ftone. ( See thefe 

 articles in the preceding volumes, and in the Addenda. ) In the 

 Britilh Mufeum, thefe minerals are clafled together under 

 the name of grenatic fubftances, whereby the confufion of 

 making the fame word reprefent both the genus and fpecies 

 is avoided. 



Glance-Coal, Anthracite. The coal which has a fplen- 

 dent luftre, and burns without flame. (See Coal.) It 

 is principally compofed of carbon, and pafles into graphite, 

 or black-lead. Werner divides glance-coal into three fub- 

 fpecies ; conchoidal glance -coal, flaty glance-coal, and colum- 

 nar glance-coal. See Coal. 



Glauber Salt, Native Glauherite ; Sonde fulphatee, Fr. 

 occurs as a mealy efflorefcence in the neighbourhood of 

 fome fait lakes, and occafionally encrufting fand-ilone and 

 marle-flate. It is fometimes ftalattitic, botryoidal, or cry- 

 ftallized in acicular cryftals. According to Reufs, the 

 glauber fait of Eger, in Bohemia, contains 



Sulphate of foda - - - 67 



Carbonate of foda - - 16 



Muriate of foda - - - 11 



Carbonate of lime " " 5 



99 



Glassy Felfpar. See Felspar, Addenda. 



Glassy Tremolite. See Tremolite. 



Gold. (See Gold.) In addition to the localities of 

 gold given under that article, we may ftate that native gold 

 is found in fome of the ftream works of Cornwall, and, like 

 the ftream tin which accompanies it, was doubtlefs once a 

 part of the metallic veins that have been deftroyed by the na- 

 tural difintegraftion of the rocks which thefe once interfeft- 

 ed. We have feen globules of native gold the fize of a pea 

 in a matrix of quartz, in the poflcffion of the Rev. Mr. Hennor, 

 of Plymouth. 



Native gold was found in alluvial foil in various parts 

 of Scotland, and was once extenfively worked at the lead- 

 hills. In the time of queen Elizabeth, it is faid that three 

 hundred men were employed in fearching for it, and that in 

 the courfe of a few fummers a quantity was collefted equal 

 to 100,000/. fterling. Gold was obtained a few years fince 

 in a ferruginous fand in Ireland, near Arklow, in the 

 county of Wicklow. One mafs of pure gold weighing 

 twenty-two ounces was found, which was the largeft 

 piece hitherto difcovered in Europe. The total amount 

 of gold exported to Europe annually from the Spanifti 

 and Portuguefe colonies in America is ftated by Humboldt 

 at 45,580 pounds troy, of which 25,000 pounds weight 

 comes from the Spanilh colonies ; the remainder from the 

 Portuguefe, principally from the Brazils, where it is col- 

 lefted by wafliing the fands of rivers and alluvial depofits. 

 Gold is found almoft every where along the feet of thefe 

 immenfe mountains which run in a chain nearly parallel 

 with the coaft, from 5° to 30° of fouth latitude. Many of 

 the filver-ores in Anaerica are alfo rich in gold. (See 



SlLVSR.) 



