Schaller — Identity of Stelznerite with Antlerite. 311 



Art. XXXI Y. — The Identity of Stelznerite with Antler'ite / 



by Waldkmar T. Schallkr. 



I 



Stelznerite was described as a basic copper sulphate by 

 Arzruui and Thaddeeff* in 1899, their papei- being edited by 

 A. Dannenberg on account of the death of Arzruni. Prof. 

 F. W. Clarke has recently called my attention to the chemical 

 identity of stelznerite with a mineral analyzed by Dr. W. F. 

 Hillebrand and named antlerite.f I have extended the inves- 

 tigation by examining optically some of the original type 

 material of antlerite in the U. S. National Museum, for which 

 privilege I would acknowledge the kindness of the Assistant 

 Curator, Dr. J. E. Pogue. All the facts obtained point to 

 the identity of stelznerite with antlerite. 



On examining antlerite under the microscope it was seen to 

 consist of a homogeneous aggregate of very minute crystals of 

 a short prismatic habit and of a pale greenish color. The 

 crystals extinguished parallel, but were too small for any 

 determination of their optical orientation. The small crystals 

 were not perceptibly pleochroic, but on the thicker ones a 

 decided pleochroisra was noticed, identical with that described 

 for stelznerite. Parallel to the elongation of the crystals, the 

 color was blue-green ; normal thereto the color was yellow- 

 green. The double refraction was high. These data are all 

 in accord with those given for stelznerite. The values of the 

 density, 3"93 (antlerite) and 3*884 (stelznerite, not corrected 

 for admixed gypsum), agree closely. 



Chemically, the two minerals are also seen to be identical, as 

 first noted by Professor Clarke. The formula deduced for 

 stelznerite is 3Cu0.1S03.2H,0 or CuS0,.2Cu(0H),,, while Hille- 

 brand calculated the more complex one, lOCuO.3SO3.7HjO or 

 SCuSO^ + '7Cu(0H)„ for antlerite. The analyses of antlerite 

 are compared with those of stelznerite in tlie table below. 

 Nos. 1 and 2 are Hillebi'and's analyses of antlerite, with 8 and 

 6 per cent, respectively, of gangue deducted, and Nos. 3 and 4 

 are the analyses of stelznerite. ISfo. 5 gives the calculated 

 composition for the formula 3CUO.ISO32H2O, while JSTo. 6 

 gives that for the more complicated formula lOCuO.3SO3.7H2O. 



Though the first analysis of antlerite agrees better with the 

 more complex formula, the second analysis agrees nearly as well 



* Arzruni, A. and Thaddeeff , K. Neue Minerale aus Chile, etc. , Stelznerit, 

 ein neues Ijasisches Kupfersulfat. Zeit. Kryst. Min., vol. xxxi p. 229, 

 1899. 



f Hillebrand, W. F. Mineralogical Notes (6. A Basic Oupric Sulphate), 

 Bull. U. S. Geol. Survey, No. 55, p. 48, 54, 1889. Also given in Dana's 

 System of Mineralogy, 6th ed., p. 928. 



