No. X. Explanation of the direction and inclination of Veins. [See the Plate.] The position of metallic veins is ascertained and described by three different angles; that of the direction, dip, and inclination. The angle of direction, or simply the direction, is ascertained by observing the point of the compass, or degree of the horizon, it tends towards, as A B, Fig. 1. The dip is the angle which it makes with the plane of the horizon, as BA E, Fig. 2. The inclination is the angle which one of its sides makes with a vertical plane, as a b c, Fig. 3; where b c represents the transverse section of the vein, and a b that of the vertical plane. This is further illustrated by Fig. 4; where A B represents the perspective view of a metallic vein. CD is the compass placed parallel to the horizon, and E F is the direction of the vein. The angle FE B is the dip, being the angle which the vein makes with the horizontal plane; and the angle a b c is the inclination, or the angle which the side of the vein makes with the vertical plane a b. No. XI. Examples of the application of the present system to Lithology and Metallogy. Of this last is that of Montmartre, which however only occurs in geods or nodules, and greatly yields in beauty to the other Structures. DOMAIN VIII. ZIRCONIC. This may be divided into two Modes, as there seems to be more silex in the jacint than in the zircon; and at any rate the mode of combination is different, else they could not be distinguished. MODE I. Zircon. STRUCTURE I. Globular. II. In various crystalline forms, which must be described. MODE II. Jacint, by the Persians called Yacut. STRUCTURE I. In round grains. II. In various crystalline forms, which form aspects, while the colours form varieties. METALLOGY. DOM. I. GOLD. II. PLATINA. IV. COPPER. DOM. V. IRON. VI. TIN. VII. LEAD. VIII. MERCURY. X. ANTIMONY. XI. ARSENIC. XV. MANGANESE. XIX. SCHEELE. XX. URANIUM, &c.&c. Dr. Thomson observes that all metals are found in the following states: 1. Metallic, either alone or combined. 2. Combined with sulphur. 3. Oxyds, that is, united with oxygen. 4. Combined with acids. Each order therefore, as he adds, may be divided into the four following Genera. 1. Alloys. 3. Oxyds. But Hauy has, on the contrary, considered each metal as a genus; and Werner, an excellent judge of metallogy in particular, considers each metal as a genus, and the various combinations as species. But as Mode chiefly implies the mode of chemical combination, it is evident that these pretended genera and species, which are wholly vague as being derived from an analogy merely imaginary between inert and animated nature, are most properly and peculiarly Modes. The Aspects are equally applicable as in Petralogy and Lithology. The Structure is also applicable to the composition in general; as in struc • Another name would be prefer. able. In the Greek titan is lime. tura verborum it is classically applied to very small objects. METALLOGY. DOMAIN I. GOLD. NOME I. ALLOYS. MODE I. Pure, or rather entire, for it always contains silver or copper. STRUCTURE I. Massive. Diversities, 1. in rocks; 2. in pepitos, or detached masses found in clay or sand, &c. STRUCTURE II. Disseminated in rocks, sands, &c. STRUCTURE III. Crystallised. Aspect 1. In cubes, or other regular forms. like Aspect 2. Dendritic, branches, leaves, &c. STRUCTURE IV. Earthy, of a brownish red, like Spanish snuff. MODE II. Electrum, or greatly alloyed with silver. STRUCTURE I. Compact, Dendritic. MODE III. Alloyed with antimony. MODE IV. Alloyed with the Sylvanite of Kirwan, so call ed from Transylvania, where it is found; the Tellurium of Klaproth but Kirwan's appellation is received by Werner. See Lion. p. 14 (as already quoted), where he says the natural knowledge of stones arises from their structure, the chemical from analysis. 635 STRUCTURE 1. Problematic Gold. STRUCTURE II. Graphic Gold. There are many other alloys. The Sulphurets of gold are very doubtful, as it may be separated by mechanical means. There are no Oxyds nor Salts. DOMAIN V. IRON. NOME I. ALLOYS. MODE I. Alloyed with Nickel. II. Alloyed with lead, &c. NOME II. SULPHURETS. MODE III. Pyrites. STRUCTURE I. Massive. Aspect 1. Common. 2. Hepatic. STRUCTURE II. Crystallised. MODE IV. Magnetic Pyrites. NOME III. OXYDS. MODE V. Magnetic Iron stone. STRUCTURE I. Compact. II. Laminar. III. Crystallised. IV. Iron Sand. MODE VI. Specular Iron Ore. STRUCTURE I. Massive. II. Crystallised. III. Micaceous Iron MODE VII. Red Iron-stone. STRUCTURE I. Scaly. II. Red Ochre. III. Compact. STRUCTURE IV. Red Hematites. MODE VIII. Brown Iron stone. STRUCTURE I. Scaly. II. Ochraceous. III. Compact. IV. Brown Hematites. MODE IX. Spathose. STRUCTURE I. Amorphous. MODE X. Black Iron Ore. STRUCTURE I. Compact. II. Black Hematite. MODE XI. Clay Ore. STRUCTURE I. Ruddle, or Red Chalk. |