131 



MISCELLANEOUS. Case 91. 



Corundum, oxide of aluminium, AIoOq, and an impure black Corundum, 



Emery, 

 variety containing iron ores, known as emery, are largely used as 



abrasives. They are now, however, being superseded by 



carhorundinn, a silicide of carbon, artificially produced at 



i^iagara Palls, which is harder than any natural substance other 



than the diamond.* Emery is produced principally in Asia 



Minor (7514) and Greece (9979 j. 



9001, crystallised carborundum. 



Varieties of corundum, not of commercial value, will be found 

 among the oxides in case 2d. 



Wyoming. ■ Alum. 



Washington. Crystal Sand. 



Ehiwlas, IN'orth Wales. Ehiwlas 



Gloucestershire (Eng.) Building 



Stones. 



Williamsite, a variety of serpentine ; Maryland marbles. Ornamental 



Stones. 



Oirt/a: marilef ; a variety of calcareous tufa (travertine), 



shoAving various markings and colouration, and capable of 



receiving a good polish : California, The best varieties come from 



Mexico, where it is associated with hot springs. 



Cornwall, Sussia, North Cai'olina, Canada, Tasmania. Kaolin. 



In addition to kaolin itself, the Cornish: exhibit includes 

 various qualities of the disintegrating granite from which it is 

 derived. 



jSfative 8iil_phur frequently results as a product of volcanic CaSGS 



action. Large quantities are won from the crater of Etna (Sicily). 91, 122, 



In pyramid case 108 will be found a series of specimens show- lOo. 



, ... Sulphur, 



ing the crude Sicilian sulphur, and the commercial varieties 



* It is stated that a carbide of titanium has now been prepared, whicli is harder than 

 diamond. 



t Tlie true onyx is a ver3' different mineral — a variefj- of chalcedony. 



