COMMON MINERALS AND VALUABLE ORES. 



3— MINERALS CONTAINING CARBON. 



THEO. F. BROOKINS, B. S., 

 Principal Au Sable Forks Union Free School and Academy, New York 



ftMONG minerals of economic im- 

 portance carbon minerals hold 

 the unique position of being 

 at the same time of the most 

 common and the most rare occur- 

 rence. As far as external appear- 

 ance indicates, a piece of com- 

 mon coal and the most brilliant dia- 

 mond are widely separated; with re- 

 gard to chemical composition they are 

 closely related. Intermediate between 

 the coal of the stoke furnace and the 

 " brilliant " of the jewelry shop is still 

 another well-known form of carbon, 

 the graphite of the lead pencil. These 

 three substances comprise the far 

 greater part of carbon-containing min- 

 erals. 



In so far as our mind's picture of a 

 mineral is that of an aggregation of 

 crystals of fairly perfect form our con- 

 sideration of coal as a mineral is erro- 

 neous. We must yield to a broader 

 interpretation of the essential charac- 

 teristics of a mineral and modify our 

 idea so as to include any homogeneous 

 substance (solid, with the single ex- 

 ception of mercury) of fairly definite 

 chemical composition " occurring in 

 nature but not of apparent organic 

 origin." Organic substances are those 

 that are alive or have lived. 



Vegetation is, undoubtedly, the origin 

 of all coal, but often much more than 

 a cursory examination is necessary to 

 prove such origin. In the less altered 

 coals the vegetable origin is readily 

 proved by the actual presence of seeds, 

 plant fibers, and other equally apparent 

 organic remains. A microscopic study 

 is necessary for finding the presence 

 of woody fiber in the more metamor- 

 phosed form. The word metamor- 

 phose comes from the Greek; tncta 

 means after or over; morphe is form. 



A metamorphosis is a change of form 

 or a forming over. 



The history of the discovery of the 

 value of coal as a means of producing 

 heat and of the development of the 

 coal-mining industry covers a compar- 

 atively recent period. Coal occurs in 

 such quantities near the surface of the 

 earth's crust and its outcrops are so 

 numerous that it cannot have failed to 

 attract the attention of the most an- 

 cient of peoples. Indeed, that coal 

 could be used as a fuel is mentioned 

 by a writer, Theophrastus, who lived 

 300 years B. C. The ancient Celts of 

 Britain are reputed to have evidenced 

 knowledge of the industrial value of 

 coal. It was not until near the middle 

 of the thirteenth century, however, 

 that coal became so important an eco- 

 nomic product as to result in statutes 

 granting to certain places the privilege 

 of mining it. After a long period of 

 trial in England the superiority of coal 

 over other fuels was recognized, and 

 stone coal, as the harder form was 

 commonly known, came into general 

 use. In America bituminous, or soft 

 coal, was mined to a slight extent in 

 the latter half of the eighteenth cen- 

 tury. The form now commonly used 

 in house-heating furnaces, anthracite, 

 for a long time baffled the colonists in 

 their efforts to m ike it burn. The 

 knowledge that an anthracite fire is 

 most effective if not continually poked 

 is said to have been acquired generally 

 by accident. 



Europe and the United States to-day 

 produce practically all the coal of the 

 world. In Europe, Great Britain, Ger- 

 many, France, Austria-Hungary, and 

 Belgium are the main sources of sup- 

 ply. Several important coal areas ex- 

 ist in our own country, notably that of 



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