212 J. W, Judd — On Yolcanos, 



mineral species as the flanks of Vesuvius and the cliffs of Somma ; 

 and as second only to it we may probably rank the mountain of 

 Monzoni. Strange to say, the species and varieties of minerals 

 found at these two localities have very much in common. This 

 will be clear to any one who is acquainted with the ordinary Yesuvian 

 miinerals, and will compare the following list of those which have 

 been obtained at Monzoni. 



MiNEKALS OP Monzoni. 



Augite. 



*rassaite (pseudomorplis after Mon- 

 ticellite.) 



SaMite (Pp'gom). 



Epidote (Pistacite). 

 ^Garnet (Grossular). 

 *tSpmel. 



Pleonaste. 



Ceylandite. 

 +Vesuvian. 

 fGehlenite. 



Mica. 

 *tBiotite. 

 *Wollastonite, 



Orthoclase (Adularia). 



Anortliite. 



Labradorite. 

 *Braiidisite. 



Scapolite, 



* 



MonticeUite (Batrachite). 



* Serpentine. 



*Vorhauserite. 



fGymnite. 



Axinite. 



Zircon. 

 *Titanite. 



Prelinite. 



Chabasite. 



Laumonite. 



Thomsonite (Comptonite). 



Apatite. 

 i-Brucite. 



Quartz. 



Calcite. 

 *Magnetite. 



Specular Iron. 



Iron Pyrites. 



Copper Pyrites. 



The species marked '•'' are most usually found in connection with 

 the more basic varieties of the Monzonite, those with the j* more 

 commonly occur near the acid varieties of the rock. 



At first sight, no localities would appear to offer greater points 

 of dissimilarity than the lava slopes of Vesuvius and the dark rugged 

 granitic mass which rises in the very heart of the brilliant white 

 pinnacles of the far-famed Dolomite Mountains ; and yet, as we shall 

 proceed to show, there is much in common between them, and only 

 a slight examination of the question will be necessary to convince 

 the observer that the beautifully crystallized minerals have in both 

 cases been formed under identical conditions. 



The interesting minerals of Vesuvius are found, as every minera- 

 logist is aware, by breaking up the blocks of limestone (which have 

 been blown from the crater, especially during certain eruptions, or 

 which are found in the agglomerates of Somma, the products of 

 older outbursts), and the crystallized minerals are seen lining their 

 cavities. 



The volcano of Vesuvius has been opened through the midst of 

 masses of Subapennine-limestone, and it is in the metamorphosed 

 fragments of the rock, evidently torn from the sides of the vent, that the 

 minerals in question are found. The formation of these minerals is 

 clearly due to the contact of masses of igneous rock, charged with 

 imprisoned water and various gases, with the masses of limestone 

 they have penetrated, and to the play of those chemical and crystal- 

 lizing forces, which under these remarkable conditions are called 

 into being. 



