MIX! 



257 



MINERALOGY. IV. 



CLASSIFICATION OF MINERALS I 

 OXYGEN 



ELEMENTS 



in.iy bo conveniently chinned under one of these 



.-t : 



1. Native Element*. 



II ('t>ll>|>uuds. 



3. Fluoruli'H uud I'i. 



4. Sulphide* nn<I Arsenide*. 



5. Organic Compound*. 



1. NATIVE ELEMENTS. 



are sixty-three olomonta or simple substances which 

 flefy all at: .mpts of the chemist to alter or change them. The 

 union of these elements with each other produces compound 

 .-;;ibstu.n<-i's. and overy body in Nature must either be an element 

 or a compound. Copper, for example, is an element. Hitherto 

 it has defied all endeavours to split it up into constituent sub- 



du. -til.-. H. (hardness) = 2'5 3 ; specific gravity = 12 20. 

 Although we say this metal appear* " natire," yet it is seldom 

 perfectly pure, generally being alloyed with silver or copper. 

 This accounts for the variation in the specific gravity. It u 

 found in alluvial detritus that U, in a deposit which has been 

 placed in it* position by water at a recent period, speaking 

 geologically. It appears either in grain* or nuggete, having 

 been washed out of its original matrix when the water which 

 produced the detritus wore down the quartz in which the gold 

 was embedded. Its original position seems generally to have 

 been in quartz veins which traverse metamorpbic rocks. 



SILVER. Native silver is also of the monometrio system. II 

 = 2-53 ; sp. gr. = 10'3 10' 5. It appears generally in filiform 

 and arborescent shapes, often alloyed with gold or copper. The 

 silver rootlets penetrate rocks usually in the neighbourhood of 

 dykes. The mines of Kongsberg, in Norway, yield fine specimens. 

 The largest mass ever found was obtained in the Uuantajays 



THE KOH-I-NOOE, OB MOUNTAIN OF LIGHT. 



stances. Occasionally this metal appears as copper that is, in 

 its native state, but most usually it is found compounded with 

 other elements oxygen, sulphur, carbon. In copper pyrites, 

 the copper ia in chemical combination with sulphur ; and a new 

 body, having a totally different appearance from either sulphur 

 or copper, is found. In malachite, again, the metal is joined 

 with oxygen and carbon, making a carbonate of copper. The 

 copper, sulphur, oxygen, and carbon are elements ; and the 

 pyrites and malachite are compounds. Some, indeed most 

 bodies, are never found in their native or elementary state. 

 The reason of this is, that the affinity they exhibit for oxygen, 

 or some other element, is so great, and the opportunities they 

 have of obeying the impulse BO numerous, that it becomes a 

 certainty that the union of the two elements will be made. An 

 example of this is seen in the case of iron. If a piece of that 

 metal be at all exposed to the air, it soon rusts ; or in other 

 words, the oxygen of the air having a great affinity for iron, 

 enters into combination with it, and forms the oxide of iron, or 

 rust. But a piece of gold will not lose its brightness, though it 

 be exposed to the air for years, since oxygen has scarcely any 

 affinity for gold. Enough has already been said to indicate 

 that but few minerals are elements ; however, there are some. 



GOLD always appears native, never as an ore. It crystallises 

 10 the monometric system, in cubes or octahedra. It is very 



147 *' 



mines in Peru : it weighed 8 cwt. Beautiful specimens are found 

 with native copper near Lake Superior. The filaments of the 

 silver interlace the copper rootlets. This fact seems to point to 

 electricity as the depositing agent, for if the metals had been in 

 a fused state they must have become alloyed with each other. 



PLATINUM. Native platinum is of the monometric system. H. 

 = 4 4'5 ; sp. gr. = 16 19. Sometimes it is found in cubes, and 

 like gold appears in alluvial gravel, being usually alloyed with 

 some of the rarer metals indium, rhodium, osmium, palladium. 

 It was first discovered in the deposits of Choco, in South America, 

 where it received its name platina, little silver. Since then it 

 has been supplied from the gravels at the foot of the Ural 

 Mountains, and so plentiful was the yield that platinum was 

 once used for corns in Russia. Its great infusibility, and its 

 power of withstanding the effect of acids, make it valuable to 

 the chemist. 



NATIVE QUICKSILVER is sometimes found in small globules 

 mixed with the matrix in which is the ore cinnabar. No doubt 

 the presence of the metal is due to the reduction of the ore by 

 some cause or other. 



IRON, associated with nickel, is found native in metoorio 

 stones. 



LEAD, TIN, BISMUTH, ARSENIC, and ANTIMONY hsve been 

 found native in very small quantities. 



