Practical Mineralogy Simplified: For Mining Students, Miners and Prospectors

Voorkant
J. Wiley & sons, 1911 - 162 pagina's
 

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Pagina 8 - Some of these odors are garlic, like that given by arsenic and its compounds when heated; sulphurous, or like the smell of burning sulphur; fetid, or like decaying eggs; and argillaceous, or like clay. These properties are sometimes very characteristic of certain minerals and greatly assist in their determination. Specific Gravity is the comparison of the weights of equal volumes of water and other substances.
Pagina 27 - Lustre metallic, often brilliant. Generally compact or massive. No cleavage. Fracture uneven. Hardness, 3 to 4. Specific gravity, 4.4 to 5. Brittle. Gives the copper flame color. Pops and breaks, or decrepitates, when heated. If pulverized and roasted with sodium carbonate it will yield a globule of metallic copper. When tetrahedrite is roasted on charcoal before a blowpipe it fuses and coats the charcoal a white color near the mineral. The mineral is distinguished from chalcocite and...
Pagina 82 - Determined generally by a few of its physical properties and blowpipe tests. The mineral is not important. It may be well to say here that some of these minerals are not common, and probably should not be taken up in this discussion. However, they are not considered rare, as most of them are found in some localities, in quite large quantities, and most of them are used in a commercial way. They are not simply used as museum or laboratory specimens for study, but enter the field of useful or economic...
Pagina 67 - In concluding the discussion on the antimony minerals it may be well again to say that stibnite is the principal ore, and since the late revision of the tariff schedule, the antimony mines in the United States are being worked and an antimony property, if at all well situated for transportation, is now worth having. ARSENIC MINERALS '} The real arsenic minerals that are of any value in a commercial way are few in number. There are several minerals containing more or less arsenic, such as enargite...
Pagina 29 - If a small piece of cuprite be held in a candle flame it will melt, and color the flame emerald-green. If pulverized and heated on charcoal, or in a porcelain dish, it will first blacken, then melt, and finally be reduced to a bead of metallic copper. This mineral is not very hard to distinguish from the other copper minerals. It may be taken for cinnabar, but cinnabar does not give the green flame color, and is much heavier. There are other...
Pagina 15 - Jt also somewhat resembles chalcopyrite, but chalcopyrite brittle, and gives a green flame. Gold is also taken for pyrite or iron pyrites, but the latter is quite light in color, and light in specific gravity when compared with gold, and is brittle. Iron pyrites, when ground up fine and roasted for some time, will become magnetic. Of course, none of these tests will apply to gold, with the probable exception of the color; as gold containing a good percentage of silver inclines to a whitish color.
Pagina 41 - It gives the blue flame when the mineral is scraped into the candle flame; also the odor of -burning sulphur. When galena is pulverized, mixed with sodium carbonate and roasted, it yields a metallic lead button. Galena is sometimes taken for specular or micaceous hematite. However, its being easily fusible and giving the odor of decayed eggs when a drop of muriatic acid is placed upon it, is enough to distinguish it from the iron minerals.
Pagina 44 - ... flame color. If this mineral is heated in a small bottle or phial, or what is called a closed tube, it decrepitates or breaks up with a crackling, popping noise, turns black, but becomes red, or its original color, upon cooling. This mineral is not of much importance as an ore of lead. While it contains a large per cent. of lead, it does not occur in enough localities in large enough quantities to be of any great importance.
Pagina 26 - This ore is not so widely distributed as chalcopyrite, but on account of its high copper percentage it is a very valuable ore of copper, when found in large enough quantities to be worked. The color is dark copper-red or reddish-brown on the face of a fresh fracture. It tarnishes quite readily to deep blue and purple, generally mixed. Bornite is sometimes crystallized, but is generally found in the massive state. Streak grayishblack. Metallic lustre.
Pagina 64 - The antimony minerals, as well as the .native element, all fuse quite easily, giving a dense white fume, with no definite characteristic odor. They all give a white coating on charcoal, and volatilize quite readily. The minerals are all fairly soft and have a specific gravity above 4. Antimony is used in making rubber, safety matches, fireworks, and type metal. However, this latter use is not as great as it used to be, owing to antimonial lead being secured from other sources than the antimony minerals....

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