1835.] Species of Minerals containing Barytes. 371 



If we include the strontian with the lime, the mineral is 

 obviously a compound of 



2 atoms sulphate of lime 

 5 atoms sulphate of barytes 



or (which comes to the same thing) 

 1 atom sulphate of lime 

 2£ atoms sulphate of barytes. , 

 The probability is, that this mineral has been hitherto 

 confounded with sulphate of barytes. When we find the 

 specific gravity of that sulphate stated as low as 4*2984, as 

 it is by Hatiy, or 4*136, as it is by Hoffmann, there can be 

 little doubt that the specimen examined was, in reality, a 

 calcareo-sulphate . 



2. Baryto-Calcite. — I have given this name, perhaps 

 improperly, (as Brooke had already appropriated it to 

 another mineral) to another species of calcareous sulphate 

 of barytes, which occurs in Yorkshire, between Leeds and 

 Harrogate, connected with the millstone grit and moun- 

 tain limestone which occur in such abundance in that 

 country. But I state this as the situation solely on the 

 authority of the mineral dealer from whom I purchased the 

 specimen. 



Colour, white, with a slight shade of blue ; texture, foli- 

 ated ; translucent when in thin plates ; lustre, silky ; hard- 

 ness, 4* ; exceedingly brittle, and very easily frangible. 

 Specific gravity 3*868* 



Its constituents, by my analysis, are 



Sulphate of lime . . 71*9 or 4| atoms. 

 Sulphate of barytes . 28*1 ,, 1 atom. 



"100- 



The foreign matter amounted to about 1J per cent. It 

 consisted of ironshot sand, probably introduced by the infil- 

 tration of water. 



3. Sulphato- Carbonate of Barytes. — This mineral occurs 

 in Brownley Hill mine, in the County of Cumberland. I 

 first saw it in a collection of minerals exposed for sale in 

 Glasgow in November 1834, by Mr. Cowper, a mineral 

 dealer from Alsten Muir. Colour, snow white. 



The specimen consists of a cengeries of very large six-sided 

 prisms, terminated by low six-sided pyramids. The surfaces 

 were so rough and irregular that it was impossible to measure 



2 b 2 



