NOTES ON ANGLESITE, ANTHOPHYLLITE, CALCITE, 

 DATOLITE, SILLIMANITE, STILPNOMELANE, TETRA- 

 HEDRITE AND TRIPLITE. 



By Eael V. Shannon, 

 Assistant Curator, Department of Geology, United States National Museum. 



ANGLESITE CRYSTALS FROM GUNNISON COUNTY, COLORADO. 



A specimen in the United States National Museum (Cat. No. 

 83,588) , which was received from the United States Geological Sur- 

 vey in 1895, contains numerous small crystals of anglesite. This 

 specimen was collected by S. F. Emmons in the Daisy Mine, Redwell 

 Basin, Gunnison County, Colorado. 



The specimen consists of a mass of ocherous and cellular limonite, 

 upon and in the cavities of which the anglesite crystals are scattered. 

 These crystals, which reach an extreme diameter of about 7 milli- 

 meters, are all identical 



mbination but 



V^ 



Fig. 1.— Crystal of anglesite. 



in CO 



differ slightly in form, / \ o "'^ 



the larger individuals 

 being tabular parallel 

 to d{102), while the 

 smaller and more per- 

 fect crystals are pris- 

 matic by elongation par- 

 allel to the b axis, the appearance being as illustrated in figure 1. The 

 forms identified on these crystals are as follows: Pinacoids, c (001). 

 5(010). Prisms, 7^1(110), x(130). Domes, o (Oil), t?(021), <^( 102)! 

 Pyramid, s(132). 



The faces of the prism x{lS()) and the pyramid s(132) are com- 

 pletely rounded and etched. The remaining faces are brilliant and 

 yield excellent reflections of the signal, although the dome d{102) is 

 commonly striated parallel to the elongation. 



ANGLESITE CRYSTALS FROM THE TINTIC DISTRICT, UTAH. 



The anglesites from the Tintic district are now rather widely dis- 

 tributed and are consequently well known. They have been de- 

 scribed by Farrington,^ Rogers,- and Hiilyak.^ The extreme varia- 

 bility of anglesite in form and habit makes it profitable to examine the 



1 FaiTington and Tillotson, Fjeld Col. Mus. Pub. 3, vol. 7, p. 131, 1908. 

 = Rogers, A. P., School of Mitis Quart., vol. 23, p. 135, 1902. 

 8 Hulyak, Zeitsch. Krj St., vol. 36, p. 201. 



Proceedings U. S National Museum, Vol. 58— No. 2345. 



437 



