THE MINERAL COLLECTOR 



•53 



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THE MINERAL COLLECTOR 



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Mica and Isinglass. crystallize in the monoclynic sys- 



tem. The various species are charac- 



BY R0BI2RT SPARKS WALKER, CH.VTTA- ^-ii •. 11 -ij- 



tenzed by a basal cleavage yielding 



NOOGA, TENN. tough scales, which vary from colorless 



Mica is not isinglass. There is a group to jet black. Muscovite is our common 



of minerals classified under the name mica, and is generally known by the 



mica, such as muscovite, paragonite, simple name mica. Colorless mica is 



lepidolite, biotite. etc. ; the illustration used in stove doors, for lamp chimneys, 



LARGE PIECES OF MICA OF THE Ml'SCOVPrE VARIETY. 



shows a piece of the muscovite variety, in the manufacture of insulating mate- 



the kind most familiar to our read- rial, of wall paper, of dynamite and as a 



ers. These mica minerals, consisting lubricant. In the year 1900, 70,587 



of aluminum silicate, with varying pounds of sheet mica were mined in the 



proportions of potassium, sodium, etc.. United States. 



