BERYL. 197 



silica 35-0, alumina 27*4, soda 9*1, lime 126, sulphuric acid 126, with 

 traces of chlorine, sulphur and water. The nosean afforded silica 35-9, 

 alumina 32G, soda 17-8, sulphuric acid 92, with a small per-centage 

 of other ingredients. A variety from Litchfield, Maine, afforded Dr. 

 Jackson nearly the same proportions — silica 35*4, alumina 3175, soda 

 17-6, sulphuric acid 65, with oxyd of manganese 44, and lime 1*8. 

 Hauyne comes from the Vesuvian lavas and near Rome. The nosean 

 is found in blocks with feldspar mica and zircon on the Rhine, near 

 the Laacher See. Also at Litchfield, Maine. 



7. Silicate with a Chlorid, 



SODALITE. 



In dodecahedrons like lapis-lazuli. Color brown, gray, or 

 blue. H=6. Gi=2-25— 2-3. 



Composition : silica 37 2, alumina 31*7, soda 19*1, sodium 

 4-7, chlorine 7 3 = 100. 



From Greenland, Vesuvius and Brisgau. 



5. GLUCINA. ' 



The minerals containing glucina are above quartz (7) 

 in hardness, excepting one, (leucophane,) which contains 

 largely of lime. The specific gravity is between 2*7 and 

 3*75. Excepting leucophane, they fuse before the blowpipe 

 with extreme difficulty, or not at all. 



beryl. — Emerald, 



Hexagonal. In hexagonal prisms. Usually in long, stout 

 prisms, without regular terminations. Cleavage , 

 basal, not very distinct ; rarely massive. 



Color green, passing into blue and yellow ; 

 color rather pale, excepting the deep and rich M 

 green of the emerald. Streak uncolored. Luster 

 vitreous , sometimes resinous. Transparent to 

 subtranslucent. Brittle* -H = 7*5 — 8. Gr = 

 2-65— 2-75. 



Varieties and , Composition. The emerald includes the 

 rich green variety ; it owes its color to oxyd of chrome. 

 Beryl especially includes the paler varieties, which are col- 



What is sodalite? What is said of minerals containing glucina 1 

 What is the crystalline form of beryl 1 it colors and hardness 1 

 17* 



