MINERALOGY. 



and in extremely minute cryftals, aggregated like mofs ; 

 it is opaque, foft, and fetlile. Before the blow-pipe it 

 Iplits into fmall pieces, and communicates a fmall blue 

 colour to borax. 



N'ative Minium ; Plomb oxyde rouge, Haily. — It has a 

 fcarlet-red colour. It occurs mafllve and pulverulent ; 

 when examined with a lens, it exhibits a cryftalline ftruc- 

 ture, like galena, in which it is generally found. Before 

 the blow-pipe, on charcoal it is firll converted into litharge, 

 and then into metallic lead. This mineral is probably 

 produced by the decompofition of galena, which it incrufts. 

 it has been found at Graflington, and other parts of 

 Craven, in Yorkftiire. 



Muriate of Lead, or Corneous Lead-Ore. — Its colours are 

 ^eyifli or yellowifh-white, palling into wine-yellow. It 

 occurs cryftallized in cuboidal prifms, either fimple, or ter- 

 minated by tetrahedral pyramids, or bevelled on the edges- 

 It exliibits a lamellar ftrutture, with joints in three direc- 

 tions parallel to the faces of a cuboidal prifm ; the crofs 

 frafture is conchoidal ; it has a fplendent adamantine 

 luftre ; is more or lefs tranfparent. It is very foft and 

 frangible. On expofure to the blow-pipe, on charcoal it 

 melts into an orange -coloured globule, and appears reticular 

 externally, and of a white colour when folid ; if melted 

 again, it becomes white ; and on increafe of the heat the 

 acid flies off, and minute globules of lead remain. Ac- 

 cording to KJaproth, its conftituent parts are, 



Oxydoflead 

 Muriatic acid 

 Carbonic acid and water 



85.5 

 8.5 

 6 



ylrfeniate of Lead, or Reniform Arfeniate of Lead ; Plomb 



arfenie compacfe, Haiiy Its colours in the frefh frafture 



are reddifli-brown and brownifh-red ; externally ochre- 

 yellow and ftraw-yellow ; internally the luftre is fhining 

 and refinous ; the frafture is conchoidal, inclining to uneven ; 

 it is opaque, foft, and brittle. The fpecific gravity is 3.93. 

 This ore has hitherto been found only in one mine near 

 T^^ertchinfk, in Siberia. It occurs in reniform and tuberous 

 mafles ; it is infoluble in water. Before the blow-pipe, on 

 charcoal it gives out arfenical vapours, and is more or lefs 

 perfeftly reduced. Its conftituent parts are. 



Oxyd of lead 



Arlenic acid 



Water 



Oxyd of iron 



Silver 



Silex 



Alumine 



35 

 25 

 10 



14 



7 



2 



95-5 



Filamentous Arfeniate of Lead, Plomb arfenie flamen- 

 tena, Haiiy, occurs cryilalUzed in fmall acicular prifms, 

 or in dehcate filky filaments, at St. Foix, in the department 

 of Saone and Loire, in France. 



Earthy Arjeniate of Lead occurs m crufts, in the fame 

 mine with the filamentous. Its colour is yellow ; it has an 

 earthy frafture ; is foft and friable. This ore has alfo been 

 found aflbciated with white lead-ore, copper-ores, and 

 quartz, in the hill of Horpie. in Oifans. 



Vol. XXXIX. 



Indurated Earthy Lead-Ore, Plomb carbonatee teneuz, Fr. 

 defcribed as lead-earth under the article Lead-Ores, has 

 been analyfed by John. Its conftituent parts are, 



Oxyd of lead ... 

 Carbonic acid ... 

 Water . , . . 

 Silex .... 



Alumine - - - . 

 Iron and oxyd of manganefe 



This ore occurs in confiderable quantities in fome of the 

 mines in Craven, in Yorkfhire, and is fmelted as a rich ore 

 of lead. 



Conchoidal Phofphate of Lead contains a fmall portion 

 of arfenie and muriatic acid. It differs from green lead-ore, 

 defcribed under the article Lead-Ore. When cryftaUized, 

 the planes of the cryftals are generally convex. It occurs 

 alfo ftalaftitic, reniform, and botryoidal. The colour is 

 orange-yellow, paffing into lemon-yellow and red ; the 

 frafture is conchoidal ; it is tranflucent ; internally the 

 luftre is Ihining and refinous. Its fpecific gravity is 7.26. 

 According to Langier, its conftituent parts are. 



Oxyd of lead 

 Phofphoric acid 

 Arfenie acid 

 Muriatic acid 

 Water 



According to Rofe, 



Oxyd of lead 

 Phofphoric acid - 

 Arfenie acid 

 Muriatic acid 



76.8 



9 



4 

 7 

 1-5 



98-3 



77-5 



7-5 



12.5- 



1-5 



99 



This ore has been found in Huel Unity mine, Cornwall. 



The greateft quantity of lead is raifed in England of 

 any country in Europe. The following table contains the 

 annual amount of lead in quintals from the following 

 countries: 



Lead io Quintals. 



Great Britain - - 250,000 



France . - - - 60,000 



Weftphaliain 1809 - - 59>77i 



Auftrian dominions - 45.809 



Spain . . - - 32,000 



Pruffia, after the treaty of Tilfit 1 2,992 



Saxony in 1808 - - 10,000 



Ruffia . - - - 10,000 



Bavaria and the Tyrol • 4<^ 



480,972 



Leelite, a mineral very recently difcovered at Gry- 



phyla, in Sweden, of which we have only the following 



defcription. It has a red colour, the luftre and tranf- 



4 C parencj- 



