TOURMALINE. 



187 



onite is abundant at Willsborough and Lewis, Essex county, 

 N. Y. ; it occurs also at North Madison, Conn. \ 

 I The garnet is the carbuncle of the ancients.J The ala- 

 bandic carbuncles of Pliny were so called because cut and 

 polished at Alabanda, and hence the name Almandine now 

 in use. The garnet is also supposed to have been the hya. 

 cinth of the ancients. 

 I Uses. The clear deep red garnets make a rich gem, 

 and are much used. Those of Pegu are most highly valued. 

 / They are cut quite thin, on account of their depth of color. 

 An octagonal garnet, measuring 8£ lines by 6^ has sold for 

 near $700. The cinnamon stone is also employed for the 

 same purpose. Pulverized garnet is sometimes employed as 

 a substitute for emery. When abundant, as in some parts of 

 Germany, garnet is used as a flux to some iron ores. 



Pliny describes vessels, of the capacity of a pint, form- 

 ed from large carbuncles, " devoid of luster and transparen- 

 cy, and of a dingy color," which probably were large gar- 

 nets. 



Pyrope or Bohemian garnet. Occurs usually in rounded grains, re- 

 sembling a rich garnet, but the primary form is supposed to be the cube. 

 Cleavage none. H=75. Gr=369 — 3'8. Composition : silica 43" 0, 

 alumina 223, oxyd of chromium 1*8, magnesia 18"5, protoxyd of iron 

 8"7, lime 57 ; and, according to Apjohn, there are also 3 per cent, of 

 Fttria. From Bohemia, in trap tufa. 



Hclvin., a wax yellow garnet-like mineral, occurring in tetrahedral 

 crystals. From Saxony and Norway. 



TOURMALINE. 



RJ^p^^PB^^? 6 ^ Usual in prisms terminating in a low 

 \ pyramids f>R = 134° 1 2 3 



W e fe - BT: e=-.\Y2> 59'; 

 R: a = 141 3 30 ; e : e = 

 154° 59'. The crystals are 

 hemihedrally modified, or 1 

 have unlike secondary 

 planes at the two extrem- 

 ities, as shown in figure 



3. J They are commonly long, and often there are but three 

 prismatic sides, which are convex and strongly furrowed. 



How is garnet distinguished 1 What are its uses 1 What is said of 

 the ancient carbuncle 1 What is pyrope ? What are the usual forms and 

 appearance of tourmaline 1 



V' 



