110 W. P. Headden — Stannite, etc. 



treated with hydrie chloride, which removes the green, vitre- 

 ous portion leaving a smaller or larger portion of yellowish 

 stannic oxide, which usually preserves in some degree the form 

 of the original network and sometimes sufficiently well, to 

 show it plainly. I could observe no evolution of carbon di- 

 oxide when the powdered mass, thoroughly wet with water, 

 was treated with hydrie chloride. 



The San Antonio tin ore as described by Professor F. A. 

 Genth of Philadelphia"" suggests the same problem presented 

 here, but much more involved. In this article he calls par- 

 ticular attention to the fact that a portion of the stannic oxide 

 amounting to 3 '86 per cent of the weight of. the ore is soluble 

 in hydrie chloride and adds that " it is difficult to perceive in 

 which form this tin existed," but adduces proof that it was not 

 present as stannous oxide. 



It may justly be urged that my analyses of the Etta and 

 Peerless material are not comparable because they were made 

 by different methods. This is true only in regard to some of 

 the data given by them, it does not change the fact that the 

 constituents are the same but present in varying proportions 

 and it is also probable that no material change was produced 

 by drying at 100° as the water lost and no more was regained. 

 Until fuller and more satisfactory data can be acquired con- 

 cerning several points relative to this substance it can scarcely 

 be considered as more than a mixture containing one or more 

 hydrated compounds of copper, iron and tin related to the 

 stannates, respectively the metastannates, which are soluble in 

 hydrie chloride but for which we cannot at the present time 

 establish a formula. 



The almost complete removal of the sulphur, the green and 

 blue stains which are without doubt largely but not wholly 

 due to the copper, found both in the quartz of the Peerless 

 and to a less extent in the feldspar of the Etta, suggest that 

 some of these alteration products are soluble in water and that 

 such salts may have furnished the solutions from which the 

 stannic oxide forming the imitative forms described by Prof. 

 Genth in the article referred to was deposited. This may also 

 help to the explanation of the pseudomorphs of stannic oxide 

 after feldspar, first observed in Cornwall by Mr. Richard 

 Pearce now of Denver, Colo. It seems very probable that 

 such solutions have been the source of the stannic oxide de- 

 posited in small irregular patches on some of the spodumene 

 crystals found in the Etta Mine. 



State School of Mines, Rapid City, S. D. 



* Contribution to Mineralogy, No. XXXI, 1887. Read before American Philo- 

 sophical Society, March 18th, 1887. 



