. 160. Or THE IMPERFECTIONS OF CRYSTALS. 17 



the dimensions dimmish much in size, the individuals be- 

 come thin laminae or fibres, of which the latter very often 

 are much thinner than a human hair. 



Nay, they may even withdraw themselves entirely from 

 observation, if the third dimension too nearly disappears. 

 Yet the compound mineral can never on this account be 

 transformed into a simple one. This subject will be ex- 

 plained more at large in Section II. 



If the mass which surrounds a crystal, and this crystal 

 itself, are not homogeneous, the regularity of the latter is 

 not always impaired. A crystal which, under such cir- 

 cumstances, has retained its regular form, is said to be 

 formed imbedded, and if separated from its support, it is 

 termed a loose Crystal. 



Crystals of this kind may be taken out of the mass which 

 surrounds them, and if they do not cohere with any 

 particles of the mass, a smooth print of their form will re- 

 main. Loose crystals, if not perhaps imperfect on some 

 other account, may be considered as the most perfect pro- 

 ductions of inorganic nature. But we rarely find such crys- 

 tals. Commonly they are imperfectly formed of them- 

 selves, or part of their perfection has been lost in the con- 

 tact with the surrounding mass. Those individuals, whose 

 dimensions are nearly equal, appear in this case as round- 

 ish masses, more or less spheroidal, or as angular masses, 

 and bear the names of Grains or Angular Pieces. Both the 

 grains and the angular pieces, therefore, are nothing else 

 but crystals imperfectly formed. 



Besides these minerals, which indeed are nothing but 

 imperfectly formed crystals, there exist a great many 

 others, which likewise assume more or less a spheroidal 

 shape, or that of grains and angular pieces. These, how- 

 ever, must be carefully distinguished from real grains and 

 angular pieces, because they are not simple, but compound 

 minerals. 



Crystals which are formed in an empty space, and ad- 

 here only with some of their parts to the support, which 

 is, in most cases, different from the mass of crystals, are 



