SILVER. 



ftruAure is lefs perfeftly lamellar, the fraftiire more even, 

 and the luflre weaker. It occurs in fmall, globular, and 

 kidney-ftiaped mafl'es ; before the blowpipe it yields the" 

 fmell of garlic, peculiar to arfenic ; a globule of filvcr more 

 or lefs pure remains. The conftituent parts of thi? ore are 

 given by Klaprolh as under ; 



Silver • - 1 6 



Arfenic - - 35 



Iron - - 44 



Antimony - - 4 



Arfenical fiWer-ore ufually occurs with native arfirnic ; 

 dark red filver-ore, brittle filver-glance, lead-glance, and 

 brown blende, in calcareous fpar. It is a fcarce mineral. 



Corneous JSlnier-ore, or Horn-ore ; Argent muriate, Fr. 

 This mineral is dillinguifhed by its tranilucency ; it has a 

 waxy or gliftening lultre, is foft and tenacious, and yields 

 to the nail. From thefe charafters it is fuppofcd to bear 

 fome refemblance to horn, whence its name. The mod 

 common colours of this mineral are pcarl-jrrey, pafTinir into 

 greemfli or reddifh-blue or brown ; it acquires a brownifti 

 tarnifh. Horn-filver occurs cryitallized in fmall cubes, and 

 is fometimes, though rarely, acicular and capillary : it is 

 more commonly in laminx or fmall mafles, or forms a coat- 

 ing on native filver. It is fufible in the flame of a candle. 

 Under the blowpipe, on charcoal, it yields a globule of 

 filver, and gives out a difagreeable odour, from the efcape 

 of the muriatic acid. Its fpecific gravity is from 4.75 to 

 4.80. Horn filver-ore is accompanied with native filver, 

 black lilver-ore, brown oyxd of iron, quartz, and lulphate of 

 barytes. It is fuppofed by fome mineralogifts to be the 

 moft- recent formation of filver-ore. It occurs in veins in 

 the filver-mines of Europe and America, and in Siberia, 

 and is obferved generally to occupy the upper part of the 

 vein. According to Klaproth, it confiils of 68 parts filver, 

 21 muriatic acid, a fmall quantity of fulphuric acid, with 

 a portion of iron and earthy fubftanccs ; but the latter 

 may be confidered as accidental. Horn-filver is rather a 

 fcarce mineral. 



Vitreous Jilver-ore ; Silver-glwce, or fulphuretled ftlver ; 

 Glnjerz, Werner ; Ardent fulfure, Haiiy. Iti colour is 

 a dark lead-grey ; it is malleable, and may be cut with a 

 knife ; t!ie furface, when cut, is (hinint;, and has a metallic 

 luftre ; in itn natural (tate it has often an iridefcent tarnifli. 

 It occurs in a variety of forms, in branches, fibres, fmall 

 irregular mafl'es, and lamina:, and is alfo frequently cryftal- 

 lizcd : the cryltals are commonly the cube or oftohedron, 

 and tlie dodecahedron, with rhomboidal faces : the frac- 

 ture is flatly conchoidal. The fpecific gravity of this ore 

 is from 7.0 to 7.2 : its conftituent parts are from 73 to 8y 

 filver, and from 15 to 25 of fulphur. When raifed to a 

 red heat, the fulphur is gradually fublimed, and the filver 

 appears in filaments, dcndritical or reticulated. Many 

 minerulogills fuppofe that capillary native filver owes its 

 formation very frequently to a fimilar kind of dccompofition 

 of vitreous filver-ore. This mineral occurs in veins, and is 

 always accompanied with other ores of filver, and with 

 galena, iron pyrites, brown blende, fulphate of barytes, cal- 

 careous fpar, and quartz. It is found in almoll all filver- 

 mines in various p.irts of the globe. 



Brittle vitreous Jilver-ore ; Shrod ^Inferz, Werner ; Ar- 

 gent noir, Haiiy ; differs from the former by its brittlenefs, 

 fplendour, and colour. The colour is intermediate between 

 iron-black and dark lead-grey ; it is brightly fplendent ex- 

 ternally ; intornallv it alternates from fhiiiing to gliflening ; 

 the lultre is metallic. It occurs mafTive and diffcminated, 

 nnd ill thin fmall plates, and frequently cryitallized in fix- 

 fided prifms, variouily terminated, and in reftangular four- 



VoL. XXXII. 



fided tabid : the latter cryftals frequently interfeA eack 

 other, forming the cellular itruaure. The tabular cryftaU 

 are generally minute. The fra£lure of the maffive ritreoui 

 ore is uneven ; that of the cryltals imperfcdly conchoidal. 

 This ore is foft, brittle, and fufible by the blowpipe ; the 

 fulphur, arfenic, and antimony, are partly volatilized, and 

 a globule of imperfeftly malleable filver, accompanied with 

 a brown fcoria, remains. According to Klaproth, the 

 brittle vitreous filver-ore, from a mine near Freyberg, 

 contained 



Silver 



Sulphur 



Antimony 



Iron 



Copper and arfenic 



Earthy matter - 



66.50 



12 



10 



5 



0.50 



Jilaei fulphuretted filver-ore ; Silber fchwarx,, Werner ; 

 differs from vitreous filver-ore by its want of luftre : it 

 occurs maffive, corroded, and in powder : the frafture of 

 the former is uneven ; the ftreak (hining and metallic. It 

 yields to the knife, and is fufible into a flag, containing 

 globules of filver. 



Redftlver-ore, or Ruby ftlver ; Rotk giltigerz, Werner; 

 Argent rouge, and Argent anlimonie fulfure, Fr. The co- 

 lours of this mineral are various fliades of red, palling from 

 a bright-red to dark-red, andreddifti-grey or black. When 

 fcraped, the powder is of a crimfon colour. The cryftal- 

 lized varieties are tranflucent, or fcmi-tranfparent, and the 

 tranfmitted light is a carmine, light blood, or cochineal-red. 

 It occurs maffive, dilleminated, and in thin plates, and 

 cryftalHzed in hexahedral prifms, varioufly terminated, and 

 in dodecahedrons, with triangular faces, nearly fimilar to 

 the cryftallization of calcareous fpar, called dog-tooth fpar. 

 The primitive form of the cryftal, according to Haiiy, it 

 an obtufe rhomboid, whofe plane angles are 104° 28' and 

 73° 22', and the inclination of the faces 100'' 28' and 

 70° 32'. The frafturc is ulually uneven, and imperfeftly 

 conchoidal ; its luftre externally is fhiniog and metallic, 

 internally glimmering, fometimes metallic. It is brittle, 

 foft, yielding eafily to the knife. Before the blowpipe 

 it gives out a copious fmoke, with an arfenical fmell, and 

 leaves a globule of filver. Its fpecific gravity is about 5.6. 

 There are feveral minerals which have a red colour, and 

 may at firit fight be confounded with red filver, as the ful- 

 plinrct of arfenic, or realgar ; but this mineral become* 

 yellow when powdered. Cinn.ib3r has a greater refem- 

 blance, but the fpecific gravity is 7, and it is entirely vola- 

 tilized by the blowpipe. Red oxyd of copper has a 

 fpecific gravity of 3.9, and is ufually accompanied with 

 native copper, malachite, and brown iron oc!a-e ; it alfn 

 effervefces with nitric acid, and communicates to a folu- 

 tioii of ammonia a blue colour. By thelc charafters it 

 may be known from red filvcr-Krc. Werner has divided 

 red filver-ore into two fub-lpecies, the light and the dark. 

 Klaproth analyfed this mineral, ind fcupd it to contain, 

 only filvcr, fulphur, antimony, and oxygen. Prouil has 

 fiiewn that there are two kinds of red I'llver-ore, the one 

 containing arfenic, and the other at'iimony. The confti- 

 tuent parts, as given by Klaproth and Vauquelin, are 



Accordiu^ 



