,*kBU- 



198 



GLUCIKA. 



ored by oxyd of iron. Aquamarine includes clear beryls of 

 a sea-green, or pale-bluish or bluish-green tint. 



The beryl consists of silica 66-9, alumina 19*0, glucina 

 14*1= 100. Emerald contains less than one per cent, of 

 oxyd of chromium. Before the blowpipe becomes clouded, 

 but fuses on the edges with difficulty. 



Dif. The hardness distinguishes this species from apa 

 the ; and this character, and also the form of the crystals, 

 from green tourmaline ; the imperfect cleavage, from euclase 

 and topaz. 



\ Obs. The finest emeralds come from Grenada, where 

 hey occur in dolomite. A. crystal from this locality, 2£ 

 inches long and about 2 inches in diameter, is in the cabinet 

 ef the Duke of Devonshire. It weighs 8 oz. 18 dwts., and 

 though containing numerous flaws, and therefore but partially 

 fit for jewelry, has been valued at 150 guineas. A more- 

 splendid specimen, but weighing only 6 oz., is in the pos- 

 session of Mr.- Hope of London. It cost £500. Emeralds 

 of less beauty, but of gigantic size, occur in Siberia. One 

 specimen in the royal collection of Russia measures 4£ 

 inches in length and 12 in breadth, and weighs 16| pounds 

 troy. Another is 7 inches long and 4 broad, and weighs 6 

 pounds. Mount Zalora in Upper Egypt, affords a less dis- 

 tinct variety. 



2 The finest beryls {aquamarines,) come from Siberia, Hin- 

 dostan and Brazil. One specimen belonging to Don Pedro 

 is as large as the head of a calf, and weighs 225 ounces, or 

 more than 18£ pounds troy ; it is transparent and without a 

 flaw. 



In the United States, beryls of enormous size have been 

 obtained, but seldom transparent crystals. They occur in 

 granite or gneiss. One hexagonal prism from Grafton, N. 

 H., weighs 2900 pounds and measured 4 feet in length, with 

 one diameter ot 32 inches and another of 22 ; its color was 

 bluish-green, excepting a part at one extremity, which was dull 

 green and yellow. At Royalston, Mass., one crystal has 

 been obtained a foot long, and pellucid crystals are some- 

 times met with. Haddam, Conn., has afforded fine crystals, 



What is the composition of beryl ? What are the different varieties 

 nd their distinctions? How is beryl distinguished from apatite and 

 ourmaline? Where are the finest emeralds brought from? What ia 

 aid of the Siberian emeralds? What of the finest beryls? What ig 

 he size of some beryls found in the United States ? 



