fci2 Troo&i on the Pyroxene. 



sometimes in granular or imperfect lamillar nodules, 

 having a vitreous lustre ; it exists also in small crystals 

 or grains disseminated in the modern lavas. 



This Pvroxexe offers various appearances in the dif- 

 ferent volcanic substances which have not been altered by 

 fire. At Vesuvius, where the masses thrown out of the 

 volcano are very abundant, this Pvroxexe is sometimes 

 in small brilliant crystals in the cavities of these substan- 

 ces ; sometimes it forms granular masses intermixed with 

 Isocrase, Garnet, Mica, Carb. of Lime, Amphigene, So- 

 dalite, Metonite, &c. Among substances of the same ori- 

 gin, which exist in the volcanic tufas near Rome, at Fres- 

 cati, and Tivoli, this Ptroxexe is in large rough crystals 

 of a dark green colour, and agglutinated with Mica or Am- 

 phigene, of which the stone cutters of Rome form small 

 ornamental vases, which are sometimes very pretty, ow- 

 ing to the chatoyant occasioned by the Mica. The vol- 

 canic sands of the shores of the lakes Albano, Nemi, Bra- 

 ciano, &c. abound with small crystals of green Pvrox- 

 exe often so transparent as to be mistaken for pondota; 

 they are not rare in the volcanic sands near Andernan. 



3. ResinonsV. Pvroxexe liesi noide, HsiUy: Conc/ioi- 

 dal ilngite, Jam. It is black, greenish brown, or brown- 

 ish olive green, with a resinous lustre — its fracture is im- 

 perfectly conchoidal, it is opaque, or sometimes slightly 

 translucent. It occurs mostly in Basalt and ancient la- 

 vas ; it is in grains of various sizes, seldom larger than a 

 hazle nut. These small grains when black are easily 

 mistaken for the ferruginous oxide of titanium, which 

 substance also occurs in ancient lavas. It is found in the 

 Basalt of Fulda in Stessia, and in the volcanic substan- 

 ces of the Vogelgcberge, and Basalt of Kaisersthal in 

 Suabia, &.c. The Schlackenblende of Mr. Noze, which 



