CRYSTAL FORMS OF CALCITE FROM JOPLIN, 



MISSOURI. 



Large crystals of calcite from Joplin, Missouri, have been known 

 for some years to collectors, and have become widely distributed in 

 collections. The crystals are remarkable, not only for their size, 

 but for their transparency, varied color and the perfection of their 

 crystal form. So far as I can learn no crystallographic study of 

 these calcites has ever been published. Photographs of some of 

 the crystals, together with some general statements as to the occur- 

 rence of calcite in Missouri, are to be found on pp. 457-9 of Vol. 

 VII, of the Reports of the Missouri Geological Survey. There is 

 also mention, on p. 567 of the same volume, of calcite crystals of 

 large size occurring in Crystal Cave, Joplin, and some description 

 of the cave is given. No crystallographic details are given in this 

 account, however, the crystals being simply described as scaleno- 

 hedral or rhombohedral. The present study of some of the crystal 

 forms can in no sense be considered a complete one, since the only 

 material undertaken to be described is that comprised in the Mu- 

 seum collections, and some crystals that were kindly loaned for 

 examination, through Prof. J. P. Iddings, by the University of Chi- 

 cago. Having, however, cursorily examined a large number of 

 crystals from this locality as exhibited in collections, both in this 

 country and in Europe, I may say that I have found them to be 

 remarkably uniform in character, and hence believe the character- 

 istic forms to be largely comprised in the types here described. 

 The specimens in the Museum collection have been obtained from 

 various sources, chiefly by purchase or exchange, but some were 

 collected at the mines in Joplin during the spring of 1898 by Mr. 

 H. W. Nichols, Assistant Curator of Geology. 



LOCALITIES OF LARGE CRYSTALS. 



The large crystals known to collectors are chiefly of two types, 

 differing in color and form. Those of the type which I may desig- 

 nate as Type No. 1 are characterized by a delicate violet to wine 



yellow color, often showing within a deeper yellow or violet light. 



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