180 ALUMINA 



glassy crystals from Vesuvius, which become clouded in 

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



Elceolite (from elaion, oil) includes the dingy translucent 

 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. 



A^iui^ni^. iu xiiwiamcu sijuaic piisuis, mien leiuiintui 



^^V\ pyramids; e : e=136° 7'. Cleavage r 

 /\ e J^\\ mc ^ stmct P al 'allel with M and e. Also 



T — -r ^rl S1VP «nnl«mallav cw onVkfiV»vrma 



SCAPOLITE. 



Dimetric. In modified square prisms, often terminating in 



rather 



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== 

 5—6. Gr = 2-6— 2-75. 



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? What is the usual form of scapolite crystals? 

 What are its colors and hardness? What is its composition? flow 

 does it differ from feldspar and tabular spar? 



