CHONDKODITE. 87 



Brittle. Hardness, scratched by a quill. Sp. Gr. 

 = 2-020. 



Before the blowpipe it remains nearly unchanged, alter- 

 ing neither colour nor transparency. Besides silica, it con- 

 tains iron and a little alumina. It occurs in Scuirmore 

 cliff in the island of Rum, also in Fifeshire and in Iceland. 



CHONDRODITE. 

 GEM. 



Condrodite. HAUY. Traite*, 2de Ed. T. II. p. 476. Con- 

 drodite. Brucite. Maclureite. PHILL. p. 97. 



Hemi-prismatic. ^. P + OD = 147 48'. ?r -f oo. 



HAUY. Grains. 

 Pr 



Cleavage, = 67 48', very indistinct; also 



f r + 00. Pr + oo. 



Lustre vitreous. Colour yellow . . . brown. Trans- 

 parent ... translucent. 



Hardness = 6-5. Sp. Gr. = 3-199, of the variety 

 from Ersby. 



It is very difficultly fusible before the blowpipe. It 

 loses its colour almost entire]y, becomes opake, and shews 

 traces of fusion in its thinnest edges. The brown varieties 

 act upon the magnetic needle, particularly if the double 

 magnetism is employed. According to D'OHSSON, it con- 

 sists of 



Silica 38-00. 



Magnesia 54-00. 



Oxide of Iron 5-10. 



Alumina 1-50. 



PotasK 0-86. 



