32 



The primitive appears to be a rhomboidal prism of about 

 105% and 75° according to Haiiy. Ours are a little trun- 

 cated at the solid angles, otherwise they represent the primi- 

 tive, and are nearer so than any we have seen or heard of. 



The fractures are parallel to the primitive faces, and 

 those of the upper and lower faces are brightest, and often 

 show a sort of opaline lustre. Sometimes we can discern 

 the two diagonal fractures. Cross fracture somewhat 

 splintery, harder than Carbonate of Lime, and softer than 

 Sulphate of Barytes. The natural colour is a little milky 

 and somewhat blueish, whence Werner called it Celestinei 

 It is nearly transparent. Spec. Grav. according to Mr. 

 Clayfield from 3*88 to 3-96; the fibrous about 3*91. Ana- 

 lysis by Mr. Clayfield : 



Strontian - 116*5 



Acid - - 83*5 



A little Iron 



200 



Sulphate of Strontian was in many cabinets before this 

 discovery of Mr. Tobin, as Sulphate of Lime, or Sulphate 

 of Barytes, — among others in the Woodwardian Collection 

 at Cambridge, as I am informed by Professor Hailstone. 



It is found in Sicily, Mont-Martre near Paris, and in 

 America. Those of Sicily are said to be the finest, and 

 are columnar, not tabular like the Bristol ones. 



