- Tellure natif férrifére et aurifére. Haüy, Traité 4. 325.
- Tellure natif auro-ferrifére. Haüy, Tabl. 119.
- Gediegen Silvan. Werner.
- Gediegen Tellure. Karsten.
- Tellure métallique natif. Bourn. Catal 446.
- Native Silvan. Jameson 2. 513.
- Sylvanite. Kirw. 2. 324.
Tellurium, in a state approaching nearly to purity, is found in masses composed of minute crystals intersecting each other in all directions, of a tin-white colour and brilliant metallic lustre, accompanied by Blende, Galæna, &c. It has Quartz and Lithomarga for its matrix, and has been discovered only in one place, namely, Facebay, in Transylvania, where it is said veins of it traverse Greywacke and Transition Limestone.
It is soft enough to be cut easily with a knife, under which it feels rather waxy, but it is reduced to powder: when strongly heated it burns with a bluish flame, and evaporates in a white vapour, with a pungent odour: it is as easily melted as Lead. Spec. Grav. according to Kirwan, 5.730, or according; to Klaproth, 6.115. Its old names, Aurmn problcmaticuin and Aunnn paradoxum, were given in consequence of the small quantity of Gold it contains in comparison with the other ores of Tellurium to which it bears a great resemblance, and which, in the rye of a Mineralogist, are little else than varieties ot it.
The primitive crystal has been discovered by Bournon to be a rectangular prism with a square base, the height of which to its breadth is as seven to ten. The prism is modified upon all its edges and angles, producing a series of crystals, some of which are pecidiar to one, and some to another alloy of Tellurium. I have taken two belonging to the present from the Count de Bournon’s figures attached to his Catalogue*.
The specimen figured is in the Cabinet of Wilson Lowry, Esq. whose kindness I have before hud the pleasure to acknowledge.
- * Some of the modifications resemble such as are usually produced by a cube, but the angles are different; the octaëdron, for instance, is more acute than the regular one resulting from the cube, as will be shown when I figure the variety in which it occurs. The incorrect descriptions of the crystals given by Haüy and most Authors, has probably arisen from their minuteness and the imperfection of the specimens examined.