486 DOMAIN V. CALCAREOUS. 



Pallas in Siberia, would not now be regarded as 

 of much importance. The pretended porphy- 

 ries of Werner should, as already mentioned, be 

 simply referred to their bases ; for felspar, like 

 mica, being found in every description of rock, 

 <jan no longer be understood to alter the deno- 

 mination. 



This gypsum, supposed primitive, has a schis- 

 tose structure, and approaches to selenite in 

 purity. A pure selenite, dividing at right an- 

 gles, was discovered by Gillet-Laumont, on the 

 left bank of the Doron, above Moutiers, Mont 

 Blanc ; and in the same neighbourhood a fine 

 alabaster, and a red gypsum. This beautiful 

 snow-white alabaster easily splits in cubes, and 

 is of a peculiar texture ; it sometimes presents 

 acicular crystals of selenite, with brown spots, 

 which this excellent mineralogist suspects to be 

 ferriferous carbonate of lime*; but he did not 

 express his idea that it was of primitive forma- 

 tion. 



Gcognostic But these are minute exceptions ; and in ge- 

 neral gypsum and alabaster must be classed 

 among the Floetz, the planiform, or horizontal 

 rocks of Werner. Sulphate of lime is commonly 



* % Chaux carlonatee jaune y fcrrifere, as marked in the catalogue 

 which he gave me of several rock specimens. The precise site i 

 Salins, near Moutiers, Mont Blanc. 



