88 Count de V>o\5^^oii on the Lau77ioti'ite. 



which are all hexahedral prisms, terminated at each extremity by a 

 hexahedral pyramid. These crystals, all of which belong to the 

 elongated variety of the primitive crystal, arc placed edgeways on the 

 quartz, and though this specimen has been several years in my col- 

 lection, several of the crystals of laumonite still retain some degree of 

 transparency. 



In the collection of Mr. Richard Phillips I have seen a very fine 

 specimen from Paisley in Renfrewshire, in which the laumonite is 

 grouped with analcime, and I have a small specimen from Portrush 

 in the County of Antrim, in which it occurs with stilbite and anal- 

 cime, 



I possess a specimen of amygdaloid having a very argillaceous and 

 earthy base, from the Venetian States, the nodules of which are all 

 hollow, and have their interior surface lined with very small crystals 

 of this substance, of a dull white appearance, and very friable. 



Lastly, I have a specimen of prchnite, of a slightly yellowish green 

 colour, the crystals of which are grouped together and penetrate each 

 other in such a manner as to form spheroids ; these have their surface 

 covered by a dull white and pulverulent laumonite. This specimen, 

 which was given me as coming from China, has for its gangue an 

 earthy argillaceous rock of a greenish grey colour. * 



Thus, with this, as with many other mineral substances, it has 

 ceased to be found the exclusive production of a peculiar district, as 

 soon as attention has been particularly directed towards it. It may be 

 observed however, from what I have stated, that the laumonite affects 

 the zeolitic rocks more than any others ; and that wherever these 

 exist, we may hope to meet with it. 



J have said, under the head of specific characters, that the laumo- 



* In all the above specimens, however, of (his sul)staiice the rapidity of its spontaneous 

 efllorcsceucc is less remarkable than in those from IIucl-":oct. 



