482 • ransome: wurtzite at goldfield 



The powdered mineral, treated with water, does not react 

 alkahne with phenolpthalein and adopting the suggestion of 

 Clarke that for silicates the presence of the (CaOH) group 

 is indicated by such a reaction, the second of the above 

 two formulas becomes untenable and the formula of cebollite, 

 (8104)3. Ca5[Al(OH)2]2, is written structurally. 



/A1(0H)2 



Ca< 



>Si04 = Ca 



Ca<^ ^Ca 



Si04 



\a1(0H)2 



The mineral gelatinizes with acids and gives off water when 

 heated in a closed tube. 



Cebollite does not appear to be closely related to any other 

 known minerals. It may belong to the zeolites although it con- 

 tains a larger amount of MgO than is common in minerals of 

 that group. 



mmERALOGY. —Wurtzite at Goldfield, Nevada. F. L. Ran- 

 some, Geological Survey. 



In a report^ on the geology and ore deposits of Goldfield, 

 Nevada, sphalerite was recorded as being present in small quan- 

 tity associated with some of the gold ore. Since that work was 

 published, the studies of Allen and his associates^ and of B. S. 

 Butler^ have given new significance to the occurrence of the 

 hexagonal sulphide of zinc, wurtzite, which has generally been 

 regarded as a rather rare mineral partly, no doubt, because it 

 has been frequently overlooked. 



Allen and Crenshaw have shown that the presence of wurtzite 



' Ransome, F. L., The geology and ore deposits of Goldfield, Nevada. U. S. 

 Geol. Survey Prof. Paper 66, 1909. 



2 Allen, E. T., Crenshaw, J. L., and Merwin, H. E., The sulphides of zinc, 

 cadmium, and mercury; their crystalline forms and genetic conditions. Am. 

 Jour. Sci. (4) 34: 341-396. 1912. 



^ Geology and ore deposits of the San Francisco and adjacent districts, Utah. 

 U. S. Geol. Survey Prof. Paper 80, pp. 93-95, 149-150, and 153-158. 1913. 



