TEL
TEL
( 410 )
trahedral fummits. The cryftals are {mall andarranged in rows, generally on the furface offeme other mineral: it not unfrequently hap-pens, that to the extremities of the prifins areattached others, at right angles, giving thewhole row the appearance of a line of T urkifhletters or Perfepolitan characters; from whichcircumftance is derived the trivial name of thismineral. Externally it is fmooth, and fhiningwith a metallic luftre. Its fracture is fine-grained, uneven : its fragments are indetermi-nately angular, {harp-edged. If is foft, brittle,and eaiily frangible. Sp. gr. 5.72. It is com-pofed, according to Klaproth , of60 Tellurium30 Gold10 Silver
100.
It occurs at Offenbanya, in Tranfylvania, inveins in a mountain compofed of fienitic por-phyry and granular lime-ftone, and is accompa-nied by quartz, iron pyrites, fahlerz, andblende.
3 Supfp. Yellow native Tellurium .—-WeifsSilvanerz, Wem. Silvane blanc, Broch. Tel-lur e natif aurifere et plombifere t Hauy. Gelberz ,Karllen.
Its colour is filver-white, inclining ftronglyto brafs-yellow, and fometimes to grey. It oc-curs difleminated, and in minute, imbedded,acicular tetrahedral prifms. Externally it has abright metallic luftre, internally it is but feebly-{hining. Its longitudinal fracture is foliated,its crofs fracture is fmall-grained, uneven. It isfoft, and moderately brittle. Sp- gr. 10.67.It is compofed, according to Klaproth , of
44.75 Tellurium
26.75 Gold
19.5 Lead
8.5 Silver0.5 Sulphur
100 .
It is found at Nagyag, in Tranfylvania, inquartz and brown fpar, accompanied by thefollowing fubfpecies, and by blende, fahlerz,and copper pyrites.
4 Subfp. Black nativeTellurium. Nagyagerz,Wern. Silva fie l nmelleux , Broch. Tellure natifaurif ere et plombifere , Hauy. Blattererz, Kar-ilen.
* Analyt. Et
Its colour is between iron-black and deeplead grey. It occurs in mafs, difleminated, orcryftallized in thin longifh hexagonal tables,cellularly accumulated. Externally it is brightlyfhining; internally, lefs fo, with a metallicluftre. Its fracture is curved foliated; themaffive variety prefents coarfe-grained diftinftconcretions. It foils the fingers a little; isfoft, fedfile, flexible in thin laminae. Sp. gr.8.9. It is compofed, according to Klaproth , of54. Lead32.2 Tellurium9. Gold0.5 Silver1.3 Copper3. Sulphur
100.
It occurs at Nagyag, in Tranfylvania, in amatrix of quartz and red manganefe, accom-panied by galena, iron pyrites, blende, anti-mony, fahlerz, and realgar.
§ 2. Analsfis of Ores.
The beft analyfes that we poflefs of the ore*of Tellurium, are by Klaproth ; a to whom in-deed the difeovery of this metal is principallyowing. In order to decompofe the firft fub-fpecies, this excellent chemift purfued the fol-lowing method.
(a) The ore, feparated as much as pofliblefrom its ftony matrix, and finely pulverized,was digefted in fix parts of warm muriatic acid,to which were added, cautioufly and at inter-vals, three parts of nitric acid. The compoundacid acted violently on the ore, and took upthe whole of it except the quartzoze matrix.
(b) The acid folution being diluted with asmuch water as it would bear without decompo-fition, was combined with cauftic fixed alkali,upon which a copious precipitate fell down ;more alkali was then added, till the whole ofthe precipitate that was refoluble in this men-ftruum was taken up. There remained behinda dark-brown flimy refidue, confifting of theox yds of gold and iron.
(c) The refidue of b was then diflolved innitro-muriatic acid, to which was afterwardsadded, drop by drop, nitrat of mercury, pre-pared in the cold, as long as the precipitatethus formed appeared of a brown colour. Thisprecipitate, confifting of gold and muriat ofmercury, was then pretty ftrongly ignited in avol. ii. p. 1.