444 



MINERALOGY 



Bilin, Bohemia ; pyrope is found in the " Blue Ground " with the 

 diamond in South Africa; in New Mexico on the Navajo Reser- 

 vation, where it is associated with chrysolite. 



III. Almandite; Common Garnet; Iron aluminium garnet, 

 Fe 3 Al 2 (Si0 4 ) 3 ; FeO = 43.34, A1 2 O 3 = 20.34, SiO 2 = 36.15; but 



composition variable ; Color, 

 red to black; Transparent to 

 opaque. The clear red speci- 

 mens are the " carbuncle," 

 used as a precious garnet. 

 Large crystals of this garnet 

 are of common occurrence, as 

 at Salida, Colorado; Fort 

 Wrangle, Alaska, where sym- 

 metrical combinations of the 

 dodecahedron and the tetrag- 

 onal trisoctahedrons are ob- 

 tained. Dodecahedrons of an 

 inch in diameter are found in 

 a schist at Southbury, Con- 

 necticut. Crystals three or 

 four inches in diameter occur 



at Arendal, "and somewhat smaller specimens at Bodo, Norway. 



All the well-developed and large crystals are in a mica schist. 



IV. Spessartite; Manganese aluminium garnet, Mn 3 Al 2 (SiO 4 )3 ; 

 MnO = 42.95, A1 2 O 3 = 20.73, SiO 2 = 36.30 ; H. = 6.5 ; G. = 3.8 ; 

 Color, dark hyacinth-red to brown-red. Beautiful specimens 

 of this garnet are found at Amelia Court House, Virginia ; also at 

 Salem, North Carolina ; Haddam, Connecticut ; and Bethel, Maine. 



V. Andradite ; Calcium iron garnet, Ca 3 Fe 2 (SiO 4 )3 ; CaO = 

 33.06, Fe 2 O 3 = 31.49, Si0 2 = 35.45; in the black melanite and 

 schorlomite some of the silica may be replaced by titanium; 

 H. = 6.5 ; G. = 3.8 ; Color, various shades of green and yellow 

 to black. Demantoid is a massive green variety often polished 

 as an ornamental stone. Aplome is also a green variety found at 

 Schwarzenberg, Saxony. Topazolite is greenish yellow and found 

 at Ala in Piedmont. Polyadelphite is a brown variety found in 

 large crystals and massive at Franklin, New Jersey; it contains 

 considerable manganese. Black varieties are also found at Frank- 

 lin, while the titaniferous garnets occur at Magnet Cove, Arkan- 

 sas; and at Henderson, North Carolina. 



FIG. 484. Garnet. 



