G O L
G O L
( 513 )
or nearly fo; if the auriferous fand forms aftratum extending to a confiderable diftancebeyond the river; then it is probable that theriver has merely cut through a previous alluvialftratum holding gold, and that to endeavourto find the mine whence this metal originatedby fearching the rocks towards the fource ofthe ftream, is mere lofs of time.
A confiderable portion of the ftream goldfeems to have been contaihed in auriferous py-rites, for almoft all the fands from which thismetal is extracted are highly ferruginous, andof a deep blackifh-brown colour: the gold itfelfis moftly of a pale yellow, and is confiderablyalloyed with filver. The Peruvian, Mexican,and Brazilian rivers, are many of them ex-tremely rich in gold, as are likewife feveral ofthe ftreams on the Weftern coaft of Africa :in Europe, the Danube , the Rhine and theRhone, afford fmall quantities of this metal, andfrom feveral other of the leffer rivers it hasbeen extracted rather for curiofity than profit:the ftreams of Hungary and Tranfylvania, underthe patient management of the Zigeuners orGipfeys, yield a greater quantity of gold thanthe reft of the European rivers, yet hardlyfufficient to afford a very fcanty maintenanceto the labourers. b Of the alluvial ftrata yield-ing gold, none has ever been found comparablein richnefs to the plain of Cineguilla in theprovince of Sonora, on the Eaftern ftiore of theCalifornian gulf: this plain is about fourteenleagues in extent, and contains large lumps ofgold irregularly difperfed through it at thedepth of about 14 inches.
Sp. 2. Graphic Gold. Schrifterz. "Wern.Silvane graphlque. Broch. Jlurum graphicum.White Gold Ore of Ojfenbanya, of the older mine-ralogifts.
Its colour is tin-white with a fhade of brafs-yellow : it occurs cryftallized in fmall flattenedprifms with four or fix fides, and terminated bytetrahedral pyramids; the cryftals are difpofedin rows, and either parallel or at right angles toeach other, giving the whole a fort of refem-blance to writing (whence the name of thismineral). The cryftals are fmooth, and exhibita bright metallic luftre: the fracture is fine-grained uneven. It is foft, brittle, may eafilybe cut with a knife. Sp. gr. 5.7..
When expofed to the blow-pipe it burns witha green flame, and a copious fomewhat acridvapour, leaving behind a malleable metallicglobule. According to the analyfis of Klap-roth , it confifts of
Tellurium - 6aGold - . 20Silver - _ to
ICO
It has hitherto been found only at Offen-banya in Tranfylvania, in thin layers, upon greyquartz, in clay porphyry, and is accompaniedby iron-pyrites, grey-copper, blende, and occa-fionally native gold.
Sp. 3. White Gold Ore. WetJs Silvanerz.Wern. Silvane blanc. Broch. Yellow GoldOre of Nagy-ag.
Its colour is filver-white palling into brafs-yellow: it occurs diffeminated, and in fmallimbedded prifmatic cryftals. Externally it hasa bright lhining metallic luftre. Its longitudi-nal fraflure is foliated, the crofs fradture isfmall-grained uneven. It is foft and fomewhatdudtile. Sp. gr. 10.6.
Tellurium -
44-75
Gold - -
26.75
Lead - -
T 9-5
Silver - -
8.L
Sulphur
o -5
100.00
It has hitherto been found only at Nagy-agin Tranfylvania, where it occurs in a gangue ofquartz and brown fpar, accompanied by blende,grey-copper, and copper-pyrites.
Sp. 4. Black Gold Ore. Nagyagerez. Wern,Silvane lamelleutt. Broch.
Its colour varies from lead-grey to iron-black:it is feldom found in mafs, being generally dif-feminated in the form of fmall fcales, or longhexagonal plates, either Angle or accumulatedon each other. It has a moderately {hiningmetallic luftre. Its fracture is curved-foliated:it ftains the fingers a little, is fomewhat flexible,and very foft. Sp. gr. 8.9.
Before the blowpipe it readily enters intofufion, and the tellurium and fulphur are vola-tilized, leaving behind a metallic malleableglobule furrounded by yellowifti fccrix.
It confifts according to Klaproth ofTellurium - - 32.2
Lead - - 54 -
Gold - - - 9,
Silver - - - 0,7
Copper - - 1.3
Sulphur - - 3.
100.0
* Born, Voyage Mineral.