FIPvST FLOOK. 
57 
Copper-glance (3e) is an important ore of copper (copper 80, General 
Cinnabar (3h) is the ore from which mercury or quicksilver 
is obtained (mercury 87, sulphur 13). 
Pyrites (5d), one of the most common of minerals, is a com- 
pound of iron and sulphur (iron 47, sulphur 53). 
Erubescite (5e), Copper pyrites (5f), and Tetrahedrite, or Grey 
Copper ore (7a), are all valuable copper ores. 
III. Common salt is represented in case 8f, and Fluor, a 
compound belonging to the same division, begins at case 7e. 
IV. The next division consists of compounds of oxygen and 
includes most of the stony minerals : 
Cuprite (10a), an important ore of copper (copper 89, oxygen 
11), is at first ruby-red in colour, but is blackened by exposure 
to light. 
Spinel (lOe), in its transparent varieties, is one of the pre- 
cious stones : the deep red is the Spinel Euby (less dense and 
less hard than the true ruby), the rose-tinted is the Balas Ruby, 
and the yellow or orange-red is the Rubicelle of the jewellers : 
sometimes, too, it has a dark blue colour. On account of their 
hardness the less valuable specimens are used for the jewelling 
of watches. 
Magnetite, or Magnetic iron ore (lOf), is the richest and most 
valuable of the ores of iron, of which metal it contains 72 per 
cent. It is the natural loadstone. 
Chrysoberyl (9e) is another of the precious stones. The beauti- 
ful greenish-yellow variety, almost equal in lustre and hard- 
ness to the sapphire, is the Oriental Chrysolite of the jewellers ; 
another variety, with a peculiar play of light, is the true Cat's- 
eye; while a third, green by sunlight but red by candle- or 
lamp-light, is the stone known as Alexandrite. 
Corundum (9h), when clear and of the proper colour, is, after 
the diamond, the most precious of stones. When pure it is the 
colourless variety known to jewellers as the Lux-sapphire : but 
with very minute traces of colouring ingredient it assumes the 
richest and most varied hues ; when red it is the true Ruby; when 
azure it is the Sapphire ; while tlie yellow, green, and purple 
varieties are known respectively to jewellers as the Oriental 
Topaz, Emerald, and Amethyst ; the prefix " oriental," though 
sulphur 20). 
Collection of 
Minerals, 
