found in the Neighbourhood of Glasgow. 415 



Harmotome is 2 Al S 3 + Br S 1 * + 4- Aq. 

 Philipsite is 3 Al S 2 + (f Cal + K) S 2 + 5 Aq. 

 Morvenite is 5 Al S 4 + Cal S 4 + 1 1 Aq. 



Morvenite is transparent, while the other two are only 

 translucent. 



12. These are all the minerals in the neighbourhood of 

 Glasgow which belong to the tribe of zeolites ; they all con- 

 tain water as an essential constituent ; they all froth before 

 the blow-pipe, and they are all soluble in muriatic acid. As 

 they fill cavities in amygdaloid, there is some reason for sus- 

 pecting that they were deposited in these cavities after the 

 trap rocks had assumed their present form. There is another 

 mineral which occurs in the same situation, which contains 

 water as a constituent, and which is soluble in muriatic acid, 

 I mean the dihydrous peroxide of iron found in a trap rock 

 near Gourock. 



It has a reddish brown, and is composed of very fine 

 needles. But at St. Just in Cornwall, it occurs in crystals, 

 the primary form of which is a right rhombic prism. It has 

 an imperfect metallic lustre, is harder than apatite, and has a 

 specific gravity of 4>'375. Its constituents are, 

 2 atoms peroxide of iron 10 

 1 atom of water 1*125. 



Carbonate of magnesia has also been found recently at 

 Bishoptown ; I am not aware of its having been observed in 

 any other part of Great Britain. It abounds in Hindostan, 

 and Hoboken in New Jersey ; in both places in serpentine. 

 About two years ago I got a great many very pure specimens 

 from Madras, for which I was indebted to Dr. Cole. 



There are twenty other species of minerals which occur in 

 the trap rocks in this neighbourhood ; some of them as veins, 

 others making one of the constituents of the rocks. The 

 veins often contain water as a constituent, though not always. 

 But those minerals that enter as constituents into the rocks 

 are destitute of water. 



As veins we have sulphate of barytes, calcareous spar, fi- 

 brous sulphate of lime, arragonite, Wollastonite and prasolite. 



1. Fine specimens of arragonite are found at Lead Hills. 



2. The name Wollastonite has been applied by Haiiy to 

 bisilicate of lime, the table spar of Werner. But as this new 

 name has not been generally adopted, and as mineralogy lies 

 under the deepest obligations to Dr. Wollaston, I have 

 given his name to a mineral found in considerable quantity in 

 veins in a greenstone rock near Kilsyth, not far from the 

 great canal, and which Lord Greenock has also found near 

 Edinburgh. 



