AET. 3. BLACK SANDS FROM IDAHO SHANNON. 5 



Not extracted by a common magnet — Continued. 

 Opaque or nearly so — Continued. 

 Color black — Continued. 



Form orthorhombic, prismatic, or tabular : 

 Crystals brilliant; columbite. 

 Crystals dull, pitted ; samarskite. 

 Crystals with light external coating; polycrase. 

 Form monoclinic, prismatic : 



Crystals vitreous, sharp ; allanite. 

 Crystals frayed to fibrous ; hornblende. 

 Form broken or irregular ; limonite, hematite, ilmenite, tapiolite, 

 cassiterite, rutile, columbite, samarskite, polycrase, uraninite, 

 etc. 

 Color gray to white, luster metallic : 

 Grains malleable ; platinum metals. 

 Grains brittle ; arsenopyrite. 

 Color yellow, luster metallic : 



Grains clear yellow, malleable ; gold. 

 Grains pure yellow, brittle; chalcopyrite. 

 Grains greenish yellow, brittle; pyrite. 

 Transparent to translucent : 

 Color red : 



Deep red to nearly black, form prismatic or irregular ; rutile. 

 Light rose to brownish red: 

 Form isometric ; garnet. 

 Form tetragonal ; zircon. 

 Color brownish to vermilion red or grayish, translucent to nearly 

 opaque, form irregular ; cinnabar. 

 Color yellow : 



Pale yellow to greenish yellow : 



Form monoclinic, flat; titanite. 



Form orthorhombic, prismatic ; olivine. 



Form broken or irregular: 



Luster greasy ; titanite, scheelite. 

 Luster vitreous ; olivine. 

 Amber yellow to brownish yellow: 

 Form monoclinic : 



Habit prismatic or equidimensional ; monazite. 

 Habit pyramidal, very flat thin ; titanite. 

 Form broken or irregular: 



Luster resinous ; monazite. 

 Luster greasy ; titanite. 

 Luster dull ; scheelite. 

 Color green : 



Deep green to dull green, form prismatic, frayed, or fibrous ; horn- 

 blende. 

 Bright green to yellow green and yellow : 

 Form orthorhombic, prismatic ; olivine. 

 Form monoclinic: 



Habit thin, flat ; titanite. 

 Habit prismatic : 



Luster resinous ; monazite. 

 Luster vitreous ; augite. 



