294 Dr. R. D. Thomson, on the [April 



The amygdaloidal cavities contain numerous species of 

 various classes of minerals, but those which are of very 

 common occurrence are included under these genera. 



CLASS I. ACIDS. GENUS, SILICA. 



1 . Rock crystal, termed Palunca in the Malabar language ; 

 Spadika in the Grantham dialect, occurs very abundantly in 

 each of the islands, in the form of crystals, varying from 

 the most minute size to half an inch in length. 



2. Common quartz. 



3. Milk and Rose quartz. 



4. Chalcedony. 



5. Amethyst. 



6. Agate. 



7. Carnelian, rare in the immediate neighbourhood of 

 Bombay. 



8. Oriental jasper, or blood stone, also rare, but abundant 

 in Guzurat and Cambay. 



CLASS II. — ALKALIES. 

 I. GENUS LIME. 



Calcareous spar. 



II. GENUS ALUMINA. 



1. Mesolite, whose composition is expressed by the 

 formula 3 Al. S + (J C + J N) S 3 + 3£ Aq. * 



2. Heulandite, observed frequently in Caranja and Ele- 

 phanta, appearing in the form of large white crystals. 



Of this last genus the number of species in India will be 

 found extremely numerous, indeed there can belittle doubt 

 that this country will afford an immense field of discovery 

 for future mineralogical investigators, nor is the scantiness 

 of our mineralogical knowledge of India so much to be won- 

 dered at, when we reflect that, as yet, scarce a single addition 

 has been made to our lists from the British possessions in 

 the East, where, of all portions of the globe, geological 

 facts point out the certainty of the greatest mineralogical 

 stores. 



The agate occurs in the form of round nodules, as well as 

 in flat waterworn cakes. The chalcedony forms a basis 

 generally upon which the rock-crystal and amethyst are 

 seated, and in one beautiful specimen procured in Caranja, 

 fine crystals of heulandite are similarly placed. The meso- 

 lite occurs in large radiated crystals, and likewise in the 



* The result of an analysis by me. Jamesons Journal, 1834. 



