NO. 2345 CONTRIBUTIONS TO MINERALOGY— SHANNON. 



453 



I. Stilpnomelane (var. chalcodite) Lambertville, N. J., analyzed by Shannon. 



II. Stilpnoraelane, Westfield, Mass., average of two analyses by Shannon. 



III. Hydromica, Rocky Hill, N. J. Clarke. Analyzed by Steiger; impurities 

 deducted. 



The differences between the two anal3^ses of the New Jersey mineral 

 are not great enough to cause surprise when the nature of the mate- 

 rial is considered. It seems possible from the description that the 

 specimen described by Clarke may have contained impurities other 

 than the 18.51 per cent calcite and 0.21 per cent titanium dioxide 

 thrown out before recalculation. The alkalies may represent a small 

 amount of feldspar or of a zeolite present as impurity, and a small 

 admixture of diabantite would be impossible of detection by other 

 means than measurements of refractive index. There thus appears 

 no valid reason for regarding the mineral as other than a partly 

 peroxidized stilpnomclane. 



Persons familiar with this mineral, and especially New Jersey col- 

 lectors, have been accustomed to refer to it by a specific name after 

 its discoverer. So far as the writer has been able to learn the sub- 

 stance is not referred to by this name in the literature and printing 

 it has been scrupulously avoided in order to keep it free, as it ethi- 

 cally now is, to be applied at some future time to a worthier species. 



