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MINERALOGY. 



plete development, whether in magnitude or perfection of 

 crystals, in the colour and limpid purity, or in any other im- 

 portant quality which may belong to it in its more excep- 

 tional occurrence. 



In a mineral collection formed and arranged with these 

 purposes in view, will be found materials of the greatest 

 interest for science, and alike for the useful and ornamental 

 arts : to the crystallographer, it offers some of the best illus- 

 trations of a most beautiful geometrical science ; to the phy- 

 sicist, it provides the material on. which some of the most 

 refined and important investigations have been and may be 

 made in connection with the theories of light, heat, mag- 

 netism, and electricity; and to the geologist, its penological 

 department presents the means for discriminating those 

 minerals, of which, though they are often only recognisable 

 under the microscope, the largest portion of the earth s crust 

 is formed. 



Here will be found, in all their variety, beauty and asso- 

 ciation, the minerals which, under the name of ores, furnish 

 the metals so essential to the needs and happiness of man ; 

 here also are specimens of the numerous minerals which, 

 whether immediately or as the sources from which manufac- 

 turers derive important products, are employed in the multi- 

 farious purposes of daily life. The suggestion that materials 

 for construction and architectural ornament, for pigments, 

 mordants and bleaching processes, that the phosphates for 

 manures, the alkalies, and the materials for the manufacture of 

 acids, are all largely dependent on the mineral resources of the 

 world, will sufficiently show how intimately a complete mineral 

 collection is connected with the arts and with commerce. An 

 illustration of the importance of a single mineral is afforded 

 by calcite or carbonate of lime : as the almost ubiquitous 

 limestone, it supplies in some of its varieties the building 

 materials of our cities, and when burnt gives quicklime, and 

 in some of its impurer forms hydraulic cement ; while in 

 other varieties it presents itself as the white and spotless 

 material used for statuary marble ; or, again, beautifully 

 and finely coloured, forms the infinitely varied ornamental 

 marbles : sometimes it appears as calc spar in a thousand 



