202 METALS. 



Eudialyte. In modified acute rhombohedrons ; vitreous and of a red 

 color. R : R=73° 30'. Transverse cleavage, perfect ; opaque or 

 nearly so. It is a silicate of zirconia, lime, soda and iron, and gelatin- 

 izes in acids. From West Greenland, in white feldspar. 



Wdhlerite. In tabular crystals of light yellow and brownish shades ; 

 sometimes transparent. Consists mainly of silica, columbic acid, zirco- 

 nia, (15 per cent.,) lime and soda. From Brevig, Norway. 



JEschynite. A titanate of zirconia and oxyd of cerium, with some 

 lime and oxyd of iron. Black and submetallic, or resinous in luster. 

 H=5— 6. Gr=4-9— 5-2. From the Ural. 



CErstedite. A titanate and silicate of zirconia. Color brown. 

 H=5*5. Gr=3.629. In brilliant crystals from Arendal, Norway. 



Malacone. Contains silica 31 3 zirconia 63'4, with water 3. Form 

 that of zircon. Gr=3 9. H=6. Appears to be a zircon containing 

 water. Color bluish white, brownish, reddish. Streak colorless. 



7. THORIA. 



The earth Thoria has been found only in a rare mineral 

 named from its constitution thorite, and in the ores monazite, 

 (p. 206,) and pyrochlore, (p. 208.) 



Thorite is a hydrous silicate of thoria. Color black to 

 resin-yellow. Powder light orange to brown. Gr=4'6 — 

 5*3. From Norway. 



CLASS VII.— METALS AND METALLIC ORES. 



General condition of Metals and Metallic Ores in nature. — 

 Metals are found either native, or mineralized by combination 

 with other substances. The common ores are compounds 

 of the metals with oxygen, sulphur, arsenic, carbonic acid, 

 or silica. For example, the oxyds and carbonate of iron are 

 the common workable iron ores ; sulphuret of lead (called 

 galena) is the lead ore of the arts ; arsenical cobalt is the 

 principal source of cobalt and arsenic. 



Only a few of the metals occur native* in the rocks. Of 

 these, gold, platinum, palladium, iridium, and rhodium, are 

 with a rare exception, found only native. The bismuth 



What is said of thoria ? How do metals occur? What are ores? 

 Give examples from ores of iron, lead, cobalt 1 What metals occuf 

 principally native 1 



* By native is understood either pure, or alloyed with other metaje, ex- 

 cluding those metals, like arsenic or tellurium, which destroy the mal- 

 leability of the metal and disguise its character. Native gold is much of 

 it an alloy of gold and silver. But aurotellurite, a compound of gold and 

 tellurium with some lead and silver, is properly mineralized gold. 



