33 



11. MoDEi-s OF Positive and Negative uniaxial indicatrices 



and of the biaxial indicatrix with sections normal and 

 oblique to optic axes. 



12. Apparatus for Electrical Heating on stage of micro- 



scope. 



13. Total Reflectometer. Moses-Weinschenck. 



14. Photographic Camera for microscope. 



Nos. I to 14 exhibited by Prof. A. J. Moses, of Co- 

 lumbia University, 



15. Barites. From the Bad Lands of South Dakota. These 



barites occur on calcite in the centre of septaria, which 

 are often nine feet in diameter. Collected by Professor 

 E. H. Babovn\ 



16. Fibrous Gypsum. From the Fort Benton clays, near New- 



castle, Wyo. Collected by H. Ries. 



17. Sylvanite Crystals (altered). From Anaconda Mine, 



Cripple Creek, Colo. 



18. Silver Ore (Polybasite) on Barite. From Aspen, Colo. 



On account of the peculiar manner in which this mineral 

 occurs, it has been called "X-ray ore." 



19. Apatite and Pyroxene in Calcite. Bradley Mines, Orange 



County, N. Y, 



Nos. 15 to 19 exhibited by Heinrich Ries. 



20. Covellite. From the copper mines at Butte, Montana. 



Several pieces obtained about i ,000 feet below the sur- 

 face. Is a brilliant, blue copper sulphide, CuS, and is 

 a rather rare mineral. 



21. Andalusite. Pink prisms one to two inches square ; from 



a great pegmatite vein that had been opened for tin ores 

 in the Black Hills, S. D. 



22. Allanite. From Mineville, N. Y. Recent discoveries of 



well bounded crystals that occur in a pegmatite vein, 

 with orthoclase and quartz. 



23. Zircons. From a pegmatite vein in the iron mines at Mine- 



ville, N. Y. 



