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Endeiolite has been met \\\[h only in the crystallized state. 

 All of the crystals hitherto found are very small, attaining at 

 the most a couple of mm. in diameter. They belong to the 

 cubic system; the octahedron is the only form that has been 

 observed. In most cases the crystals occur implanted on largei- 

 aegirine individuals, either isolated or forming continuous crusts. 

 They are in general attached by an octahedral face, parallel to 

 which they are then labularly developed, so that they stand 

 out very little from the surface on which they rest. In the 

 majority of cases they are sunk a little into their substratum ; 

 they must, therefore, have been formed simultaneously with the 

 outer layer of the aegirine crystals on which they occur. Owing 

 to this mode of occurrence the crystals are never developed on 

 all sides, but exhibit at most only three corners and the cor- 

 responding number of edges. They are, however, always 

 sharply and distinctly developed, and the faces are fairly hright, 

 though not quite even. The unevenness is generally irregular 

 consisting in low (flat) wart -like elevations. Not infrequently 

 such forms of crystal growth occur in which on an octahedral face 

 another and smaller octahedral face rises, which is conformable 

 to the main face, but may deviate considerably from a position 

 parallel to it. This sometimes gives rise to such grooves on 

 the octahedral edges as those which occur commonly enough 

 e.g. on diamond. In general the octahedral form' of the crystals 

 is fairly regular, the different faces being of about the same size. 

 Not infrequently, however, occurs a certain tetrahedral develop- 

 ment, only four faces being large, while those parallel to them 

 are very small. This ought not, however, to be considered as a 

 proof that the mineral belongs to the tetrahedral class of the 

 cubic system, since no difference in the physical properties has 

 been found to exist between the large faces and the small ones. 

 Another irregularity consists in the crystals often being elongated 

 parallel to an octahedral edge, which gives them a prismatic 

 appearance. 



