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applied axes axis belong characters colour compound form compound minerals connexion considered consists contiguous Corundum crystallographic sign crystals degree denominations derived determined digrammic dimensions dodecahedron dron edges of combination equal and similar expressed face of composition faces of cleavage forms contained four-sided prism fracture fundamental form genus gonal hedron hemi-prismatic hexahedral hexahedron homologous horizontal prism horizontal projection idea inclined diagonal individuals intersect Iron-pyrites isosceles four-sided pyramid kind lateral edges likewise limits lustre Mineral Kingdom Mineralogy Natural History natural-historical properties nerals observed obtained obtuse terminal edges octahedral Fluor-haloide octahedron parallel position particles perpendicular plane principal section prism prismatic prismatoidal produced pyra Pyrites rhom rhombohe rhombohedral Lime-haloide rhombohedral Quartz rhombs scalene eight-sided pyramid scalene four-sided pyramid scalene six-sided pyramids shew simple forms simple minerals situation solid angles species specific gravity Streak subordinate series supposed Tessular tetrahedron tion trapezohedrons triangles twin-crystal varieties of rhombohedral
Page 329 - ... science had before suffered from heterogeneous principles. The principle of classification consists in the resemblance of natural properties, since in every science the classification must rest upon such relations as are objects of the science. On the different degrees of resemblance are founded the higher ideas of the theory of the system. An assemblage of species connected by the highest degree of natural-historical resemblance is termed a genus ; an assemblage of similar genera an order ;...
Page 385 - In this case, both hardness and specific gravity are prominent characters, and exclude the individual at once from the first and third, but not from the second class : with the characters of this class, its other properties also perfectly agree. Hence the individual belongs to the second class. Comparing the properties of the individual with the characters of the orders in the second class ; hardness and specific gravity will be found too great for the order Haloide ; hardness too great for the orders...
Page 304 - Every person, however little accustomed, will experience a very marked difference, if comparatively trying in this way any two subsequent members of the above scale, and thus the difference in their hardness will be easily perceived. A short practice is sufficient for rendering these perceptions more delicate and perfect so that in a short time it is possible to determine differences in the hardness very much less than those between two subsequent members of the scale. "Upon these observations is...
Page 357 - ... names of the orders he has invented but two which are entirely new, having employed as many designations from ancient mineralogy as would answer the purpose. The names receive their signification in agreement with the ideas of the orders; thus pyrites embraces the minerals hitherto called by that name. A mineral which may with propriety bear the name of a metal must really be a metal, or it must present the properties peculiar to metals. Mica signifies a mineral which may be cleaved with facility...
Page 387 - Scheelium-ore hy its too great hardness, and too little specific gravity ; from the genera Tantalum-ore, Uranium-ore, Cerium-ore, Chrome-ore, Iron-ore, and Manganese-ore, by hardness and specific gravity, both of them being too great; as also by its uncoloured streak, which only agrees with that genus from which the individual differs most by its hardness and specific gravity. From all this we infer that the individual cannot belong to any other than to the fourth genus, and that we are therefore...
Page 305 - ... file, and determined accordingly. " The process of this determination is as follows: " First, we try, with a corner of the given mineral, to scratch the members of the scale, beginning from above, in order that we may not waste unnecessarily the specimens representing lower members. After having thus arrived at the first, which is distinctly scratched by the given mineral, we have recourse to the file, and compare upon it the hardness of this degree, that of the next higher degree, and of the...
Page 304 - ... alone is not sufficient, if we intend to make a more sure and extensive application of the characters that may be taken from hardness, than that which has hitherto been common in Mineralogy. " But if we take several specimens of one and the same mineral, and pass them over a fine file, we shall find that an equal force will everywhere produce an equal effect, provided that the parts of the mineral in contact with the file be of a similar size, so that the one does not present to the file a very...
Page 383 - Characteristic may be applied, and it will at the same time point out what other characters are still wanting; so that a mere inspection of the mineral, or a very easy experiment, as for instance, to try the streak upon a file, or still better, upon a plate of porcelain biscuit, will very often be sufficient. The given individual is now carried through the subordinate characters of the classes, orders, genera, and species, one after the other, comparing its properties with the characteristic marks...
Page 384 - ... a high degree of specific gravity, particularly if the appearance be not metallic ; and a high degree of hardness. The observation of these will immediately decide whether an individual can belong to any particular class, order, genus, or species. It is understood, that if it be not thereby excluded, the other characters must next be examined, till either an excluding one be found, or if not, the individual may be considered as belonging to that class, order, &c. with which it has been compared...
Page 385 - But the appearance is not metallic ; therefore the colour of the individual is quite indifferent ; that is, this conditional characteristic mark does not affect the individual, and consequently cannot decide. Since the appearance is not metallic, the individual must exhibit adamantine or imperfect metallic lustre. The first will be found, particularly in the fracture. The following characteristic marks refer to minerals of a red, yellow, brown, or black streak ; and as the individual gives none of...