XV. — GEOLOGY AND MINERALOGY. 123 



Silicates with Glucina, including Emerald, a rich green 

 precious stone, and Beryl or Aquamarine. 



Silicates with Zirconia, including Zircon, a rather disregarded 

 gem, very common in drift and often mistaken for ruby tin. 

 (See Catalogue pages 94 to 97, Nos. 1106 to 1132.) 



The Zeolites, including several groups of beautifully cry- 

 stallized minerals occurring chiefly in basalts. 



Clay group ; An important and useful group ; Ex. Common 

 Clay, Pipe Clay, Fire Clay, Kaolin, etc. (See Catalogue, pages 

 49 to 89, Nos. 575 to 1054.) 



When specimens included in the above subdivisions have 

 been found too large to be displayed in the flat show-cases, they 

 have been placed in special cases. 



METALLIC MINERALS. 



The classes into which the metallic minerals have been 

 divided will be found in the cases in the following order : 



Zinc, Manganese, Iron, Cobalt, Nickel, Meteorites (debris 

 of planets described further on as a special collection), Tin, 

 Titanium, Chromium, Molybdenum, Tungsten (Wolfram, &c.). 

 Uranium, Arsenic, Antimony, Bismuth, Lead, Copper, Mercury, 

 Silver, Gold, Tellurium and Selenium, Platinum and other rare 

 metals of the Platinum class. The two metalloids, Tellurium 

 and Selenium, which belong chemically to the Sulphur class, are 

 very rare, but are placed here as an appendix to gold and silver, 

 with either or both of which they are sometimes found associated 

 or combined, as well as with lead and bismuth. (See Catalogue 

 pages 105 to 206, Nos. 1161 to 2340). 



Next come the minerals which are mostly found in the rock 

 called Zircon-Syenite, and containing the rare metals Yttrium, 

 Cerium, Thorium, Tantalum, Columbium, Zirconium, &c. (See 

 Catalogue pages 98 to 103, Nos. 1133 to 1160.) 



NEW PURCHASES (NOT CATALOGUED). 



Among the Minerals which have been purchased between 1887 

 and 1889 and which are not included in the catalogue, the 

 following are the most remarkable : — 



