180 ALUMINA 



glassy crystals from Vesuvius, which lecome clouded ir 

 nitric acid. The name is from the Greek nephele, a cloud. 



ElcBolite (from elaion, oil) includes the dingy translucenl 

 or subtranslucent cleavable masses having a strong greasy 

 luster. Altered crystals from Greenland have been called 

 gieseckite. 



Nepheline contains silica 43*4, alumina 33*5, peroxyd 

 of iron 1*5, lime 0-9, soda 13*4, potash 7*1, water 1*4 

 Rounded on the edges before the blowpipe : some varieties 

 fuse readily. In nitric acid, fragments become clouded and 

 gelatinize. 



Dif. Distinguished from scapolite and feldspar by the 

 greasy luster when massive, and forming a jelly with ac.ds ; 

 from apatite by the same characters, and also its hardness. 



Obs. Nepheline occurs at Vesuvius and near Rome, in 

 lava. Elceolite is obtained at Brevig and other places in 

 Norway; also in Siberia. It is also found in the Ozark 

 mountains in Arkansas, and at Litchfield in Maine. 



SCAPOLITE. 



Dimetric. In modified square prisms, often terminating in 



/^\\ pyramids; e : 63S136 1 7. Cleavage rather 

 /\ e ^\\ mo ^ stmct parallel with M and e. Also mas- 



•"— < ^" sive, sublamellar or subfibrous. 



Colors light ; white, pale blue, green or red. 

 Streak uncolored. Transparent to nearly 

 opaque. Luster usually a little pearly. H= 

 \Q\^/ 5—6. Gr = 2-6— 2-75. 



^^^js Composition : silica 49 3 alumina 27 9 



lime 22*8. Before the blowpipe it fuses slowly with intu- 

 mescence. With borax dissolves with effervescence to a 

 transparent glass. 



Dif. Its square prisms and the angle of the pyramid at 

 summit are characteristic. In cleavable masses it resembles 

 feldspar,'but there is a slight fibrous appearance often dis- 

 tinguished on the cleavage surface of scapolite, which is 

 peculiar. It is more fusible than feldspar, and has higher 

 specific gravity. Spodumene has a much higher specific 

 gravity, and differs in its action before the blowpipe. Tabu- 



What have specimens with a greasy luster been called ] What is the 

 ffect of nitric acid 1 What is the usual form of scapolite crystals] 

 What are its colors and hardness] What is its composition? How 

 does it differ from feldspar and tabular spar? 



