538 



REPORT OF NATIONAL MUSEUM, 1900. 



let colored spinels; uiul also there are those showing a whole series of 

 intermediate hues such as pink, heliotrope, lavender, lilac, purple, 

 fawn, corn color, etc. The transparent, lively, red-colored spinels 

 are called sjnnel riih'ies^ and may readily be taken for the true rub3% 

 though its small refractive and dispersive power together with the 

 absence of pleochroism render it less brilliant than and lacking the 

 fire of the red corundums. The rose-red to pink-colored kinds are 

 called hcdas riily ,' the yellow or orange-red spinels are known asruhi- 

 ceUe; the violet and purple ones as almandine; the pale to sapphire- 

 blue kinds as sapphirine ; the blacks as pleonast 



Fig. 12. 

 SPINEL CRYSTALS. 



Kandy, Ceylon. 



SpeL-inieu No. 43103, U.S.N.M. 



Spinel occurs embedded in granular limestone, and with calcite in 

 serpentine, gneiss, and allied rocks; occurring also in cavities in the 

 ejected masses of certain volcanoes. Found also as rolled pebbles in 

 certain alluvials, such as those of Ceylon and Burma, Avhere it occurs 

 in water-Avorn masses of fine colors in the channels of streams along 

 with quartz, garnet, tourmaline, sapphire, zircon, and other gem 

 minerals. Spinel ruby is f requentl}' found along with the ruby corun- 

 dum in the crystalline limestone of the rubv mines of Burma. Most of 

 the gem spinel comes from Ceylon, Burma, Siam, India, and other 



