CRYSTALLOGRAPHIC NOTES ON GLAUCOCHROITE, WILLEMITE, 

 CELESTITE, AND CALCITE FROM FRANKLIN, NEW JERSEY 



By Samuel G. Gordon. 



On a recent trip to the famous zinc mines at Franklin, N. J. 

 the writer secured a series of specimens for the Vaux Collections 

 which included the following 

 minerals: calcite, celestite, ga- 

 lena, glaucochroite, hardy- 

 stonite, willemite, and zincite. 

 Crystallographic measure- 

 ments of the glaucochroite, 

 willemite and calcite showed 

 the presence of new forms; 

 while the celestite represents 

 a new occurrence of this 

 mineral. 



Glaucochroite 



Glaucochroite was described 

 by Penfield and Warren 1 in 

 1899. The original specimens 

 consisted of small prismatic 

 crystals in nasonite. As no 

 terminal planes were found, 

 the twin-plane (Oil) was used 

 in calculating the axial ratios. 

 Subsequently Palache 2 de- 

 scribed briefly the results of 

 measurements on two ter- 

 minated crystals. 



The specimens which form- 

 ed the basis of the present 

 study are far superior to those 

 which have been heretofore 

 found. Several large masses 

 of franklinite- willemite ore Fig. 1. Glaucochroite, Franklin, N. J. 

 contain fractures lined with small glaucochroite crystals associ- 



m 



'Am. J. Sci. 8, 343-346, 1899. 

 2 Am. J. Sci. 29, 181-182, 1910. 



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