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tendency were misunderstood, or 

 suffered to degenerate into an avi- 

 dity merely for the collecting of 

 what is brilliant or rare. To the 

 attainment of the science of geology, 

 which is intimately connected with 

 agriculture and the arts of life, that 

 of mineralogy is essentially requisite. 

 The study of mineralogy, therefore, 

 does not include only a knowledge 

 of the more rare and curious mi- 

 nerals : there is nothing in the 

 mineral kingdom too elevated or 

 too low for the attention of the 

 mineralogist, from the substances 

 composing the summits of the lofti- 

 est mountains, to the sand or gravel 

 on which he treads. 



Ey the study of what, in oppo- 

 sition to the term aggregated rocks, 

 may be termed simple minerals, 

 the mineralogist becomes enabled 

 to detect the substance with which 

 he holds acquaintance by itself, 

 when aggregated with others in a 

 mass ; and thus he becomes qualified 

 for the more difficult and more im- 

 portant study of the science of geo- 

 logy, which embraces a knowledge 

 of the nature and respective posi- 

 tions of the masses and beds com- 

 posing mountains, and, indeed, of 

 every description of country, whe- 

 ther mountainous or otherwise. 



There is no branch of science 

 which presents so many points of 

 contact with other departments of 

 physical research, and serves as a 

 connecting link between so many 

 distant points of philosophical 

 speculation as this. Nor, with the 

 exception of chemistry, is there 

 any which has undergone more 

 revolutions, or been exhibited in a 

 greater variety of forms. To the 

 ancients it could scarcely be said to 

 be known at all, and up to a compar- 

 atively recent period, nothing could 

 be more imperfect than its descrip- 

 tions, or more inartificial or un- 

 natural than its classification. The 

 Arabian writers, however, in the 



middle ages appear to have culti- 

 vated mineralogy with some suc- 

 cess; the first foundation of a 

 rational arrangement of minerals 

 was laid by Avicenna at the close 

 of the tenth century. It was only 

 when chemical analysis had ac- 

 quired a certain degree of precision 

 and universal applicability, that 

 the importance of mineralogy as a 

 science began to be recognized, and 

 the connection between a stone and 

 its ingredient constituents brought 

 into distinct notice. The arrange- 

 ment of simple minerals has always 

 been a subject of controversy with 

 mineralogists ; and the discussions 

 to which it has given rise have 

 materially contributed to the ad- 

 vancement of our knowledge of the 

 natural and chemical history of 

 minerals. Eerzelius contends for 

 the chemical arrangement, accord- 

 ing to which the species are grouped 

 in conformity with their chemical 

 composition and characters. Wer- 

 ner rejects the pure chemical, and 

 adopts the mixed method, in which 

 the species are arranged and deter- 

 mined according to the conjoined 

 external and chemical characters. 

 The writers of the Wernerian school 

 usually divide mineralogy into the 

 five following branches; namely, 

 oryctognosy, chemical mineralogy, 

 geognosy, geographical mineralogy, 

 and economical mineralogy. Of 

 late years, the arrangement accord- 

 ing to external characters alone 

 (named the natural history system) 

 has been advocated by Mohs. 

 Among the external characters of a 

 stone, none were, however, found 

 to possess that eminent distinctness 

 which the crystalline form offers ; 

 a character in the highest degree 

 geometrical, and affording the 

 strongest evidence of its necessary 

 connection with the intimate con- 

 stitution of the substance. The 

 full importance of this character 

 was, however, not felt until its 



