192 BULLETIN 118, UNITED STATES NATIONAL MUSEUM. 



Occidental chalcedony =somewhat opaque chalcedony; more opaque than oriental 

 chalcedony. 



Occidental diamond=rock crystal (quartz). 



Occidental topaz=yellow quartz. 

 ■ Occidental turquoise =bone turquoise. 



Octahedrite=titanium oxide in tetragonal crystals, with slightly different properties 

 from rutile. 



Odontolite=bone turquoise. 



Oeil de boeuf=labradorite. 



Old rock = turquoise from Persia. 



01igoclase=feldspar, aluminum, sodium, and potassium silicate. 



01ivine= magnesium and iron silicate. The word olivine is used as a trade name 

 for green garnet (demantoid from the Ural Mountains), and is also improperly 

 applied to any green stone. The following distinctions are sometimes applied 

 to the mineral olivine: Chrysolite, inclining to yellow; peridot, inclining to 

 yellowish green; olivine, inclining to green. 



Onegite= quartz with inclusions of hair-like crystals of goethite. 



Onyx=banded chalcedony with alternating bands of cloudy milk-white and another 

 color, usually black. 



Oolite = concretionary massive limestone (calcium carbonate) made up of minute 

 spherical grains. 



Opal=amorphous massive form of hydrous silica. 



Opal agate=banded opal having alternate layers of opal and agate. 



Opal jasper = jasper opal. 



Opal onyx = alternate layers of precious and of common opal. 



O palescent chrysolite = chrysob ery 1 . 



Opaline=opal matrix. 



Opaline feldspar=labradorite. 



O phiolite = serpentine. 



Orange topaz=same as Spanish topaz, smoky quartz changed to yellow by heat. 



Oregon jade=californite (vesuvianite). 



Oriental=variety of corundum (not necessarily found in the Orient). 



Oriental agate=finely marked and very translucent agate. 



Oriental alabaster= travertine. 



Oriental amethyst= purple corundum. 



Oriental aquamarine = light-green corundum. 



Oriental cat's-eye=chrysoberyl cat's-eye; also smoky corundum. 



Oriental chalcedony=very translucent chalcedony (compare with occidental chal- 

 cedony) . 



Oriental chrysoberyl=yellowish-green corundum. 



Oriental chrysolite=greenish-yellow corundum; also chrysoberyl. 



Oriental emerald=green corundum. 



Oriental garnet=almandine (garnet). 



Oriental girasol=girasol (corundum). 



Oriental hyacinth= rose-colored corundum. 



Oriental hyacinth= aurora-red corundum. 



Oriental jasper=bloodstone (quartz). 



Oriental lapis=lapis lazuli. 



Oriental moonstone = pearly corundum. 



Oriental onyx=banded, mottled, or clouded travertine. 



Oriental opal=Hungarian opal carried to the Orient by merchants and then shipped 

 back to Europe. 



Oriental peridot == green corundum. 



Oriental sapphire=(in part) blue corundum. 



