84 PHYSIOGRAPHY. 



Colour blue ... green, rather bright. Streak un- 

 coloured. Feebly translucent on the edges ... 

 opake. 



Hardness = 6-0. Sp. Gr. = 2-830 . . . 3-000, FISCHER. 



It is not dissolved by muriatic acid. Before the blow- 

 pipe it becomes brown in the reducing flame, and gives a 

 green colour to it. It is infusible by itself, but very easily 

 with borax or salt of phosphorus. According to BERZZ- 

 LIUS, it consists of phosphate of alumina and lime, silica, 

 oxide of iron and copper, and a little water. 



It is found in Persia, either in pebbles, or in small veins 

 traversing a kind of trap in its original repository. Cut 

 and polished, it is used for different ornamental purposes. 



CHIASTOLITE. 



SPAR. 



Chiastolite. JAM. Sy st. Vol. II. p. 49. Man. p. 3 1 8. Chias- 

 tolite. PHILL. p. 201. 



Prismatic. P + oo = 91 5(X. Pr = 120. HAUY. 



Cleavage, P o>. P + oo. Pr. ?r -f x. Pr + oo, 

 all of them imperfect. Fracture imperfect con- 

 choidal, splintery. The crystals present a black 

 cross in their transverse section. 



Lustre vitreous, indistinct. Colour white, grey. 

 Streak white. Translucent. 



Hardness =r 5-0 ... 5-5, if the mineral be not disin- 

 tegrated. Sp. Gr, = 2-944, HAUY. 



Before the blowpipe the whitish part of the crystals is 

 infusible, but assumes a purer white tint. It melts but 

 . difficultly with either borax or salt of phosphorus. Accord- 

 ing to BERZELIUS, it is a compound of silica and alumina. 





