UAH NUT. 



185 



cahedron rather distinct. Also found massive granular, ana 

 coarse lamellar. 



Color deep red, prevalent; also brown, black, green, 

 12 3 4 



white. Transparent to opaque. Luster vitreous. Brittle, 

 H=6-5— 7-5. Gr=3-5— 4-3. 



Varieties and Composition. Garnet is a compound of three 

 or four silicates, the silicates of alumina, lime, iron, and 

 manganese, and the varieties of color arise from their vari- 

 ous combinations. Oxyd of chrome is sometimes present, pro- 

 ducing an emerald-green variety. 



Precious garnet or almandine is a clear deep red variety, 

 and is used much in jewelry. A specimen from New York 

 afforded Wachtmeister, silica 42*5, alumina 19*15, protoxyd 

 of iron 33*6, protoxyd of manganese 5*5. 



Common garnet has a brownish red color, and is imper- 

 fectly translucent or opaque. 



Cinnamort stone, called also essonite, is of a light cinna- 

 mon-yellow color and high luster. It differs from the pre. 

 ceding principally in containing but 5 or 6 per cent, of iron 

 and 30 to 33 percent, of lime. Topazolite is another yellow 

 variety, approaching topaz in color, and presenting the form 

 in figure 3. 



Melanite (from the Greek melas, black) is a black garnet, 

 containing 15 to 25 per cent, of the oxyds of iron and man- 

 ganese. Pyrendite is another name for a black variety from 

 France. 



Manganesian garnet has a deep red color, and is usually 

 quite brittle.* A Haddam specimen afforded Seybert, silica 

 35*8, alumina 18*1, protoxyd of iron 14*9, protoxyd of man- 

 ganese 31'0. 



Grossular'tte occurs in greenish trapezohedrons ; and con- 

 tains 30 to 34 per cent, of lime with but little iron. 



Ouvarovite is a chrome garnet, containing 22*5 per cent, of 

 oxyd of chromium, and having the rich color of the emerald. 



What is the color and hardness of garnet? of what does it consist 

 what is precious garnet ? What is cinnamon stone 1 What is ouvaro- 

 vite 1 



10* 



