Dr. Mac Culloch on Mine^-al Veins. 207 



sublimed by artificial heat ; and they all admit of being cry- 

 stallized by fusion. All the sulphurets admit of being fused ; 

 all appear capable of being sublimed ; and, probably the whole 

 can also be produced in this way by a direct combination of 

 their ingredients. All the oxydes are produced from the 

 metals by heat, and some of them admit of being volatilized. 

 Under these circumstances also, some of them crystallize ; as 

 was observed in red oxyde of copper, formed in the cavities of 

 metallic vessels in Pompeii. It is probable that some of the 

 metallic salts, the arseniats for example, can be produced in 

 this way ; but I cannot quote any satisfactory experiments on 

 a subject which, in all its bearings, is well vvorthy the atten- 

 tion of those chemists who are interested in geology, and 

 whose leisure is greater than my own. 



In examining the evidence which nature affords on this 

 question, the following is a list of such earthy minerals as are 

 found in the situations above-mentioned. It is probable that 

 many are omitted, as no evidence but what seemed unexcep- 

 tionable has been taken; and, in examining the entire cata- 

 logue of minerals, it will easily be found that there are some of 

 which the origin still remains uncertain, and which are there- 

 fore excluded both from the aqueous and the igneous lists. 



Earthy Minerals. 



Quartz (by fusion and by Garnet. 



sublimation.) 



Felspar. Cyanite. 



Mica. Zircon. 



Hornblende. Fluor spar. 



Actinolite. Spodumene. ' 



Chlorite. Corundum. 



Steatite. Beryl. 



Serpentine. Topaze. 



Chrysoberyl. Tourmalin. 



Epidote. Schorl. 



Apatite. Tremolite. 



Finite. Emerald. 



Idocrase. Gabbronite. 



Anthophyllite. Wernerite. 



Andalusite. Pyrophysalite. 



Stilbite. Lapis lazuli 



Jade. Asbestus. 



Vol. XV. 



