468 Gustav Rose, on Greenstone [Dec. 



great abundance in Ural. The presence of oxide of iron, 

 which accompanies it in this locality, communicates a pecu- 

 liar interest to it. Some large magnetic mountains, as 

 Blagodat, near Kuschwa, Wisckaja Gora near Nischne 

 Tagilsk, Katschkanar near Nischne Turinsk, are surrounded 

 by augite porphyry, and appear to pass through this rock. 

 The greater part of these porphyries is augite or uralite. 

 Those containing labradorite are more rare in Ural. The 

 last are encountered, however, at the village of Ajatskaja, 

 to the north of Katharinenburg ; the basis is grayish or 

 yellowish ; the size of the labradorite varies. 



Other beautiful varieties come from Altai, and particu- 

 larly from the river Tscharysch. They surpass those of 

 Ural in beauty, possessing white labradorite and blueish- 

 green augite, with a variegated basis. Among the most 

 remarkable labradorite porphyries of other countries the 

 verde antique may be noticed. The basis is beautiful 

 green ; the crystals of labradorite are very large, but always 

 coloured greenish- white. Iron pyrites, pistagite, and quartz 

 occur in it. 



The finest varieties in Germany are found in the Hartz, 

 as between Elbingerode and Rubeland, between Blanken- 

 burg and Huttenrode. The Miihlthal, between RUbeland 

 and Elbingerode, contains also a number of rolled frag- 

 ments of this porphyry. The basis is blackish-green, and 

 sometimes reddish-brown, produced by incipient decomposi- 

 tion. The crystals are white, or greenish-white. Small 

 round pieces of carbonate of lime are found disseminated 

 through the basis. 



Porphyry containing equal parts of labradorite and augite 

 occurs at Blagodat, near Kuschwa, in Ural, and near Dil- 

 lenburg (Nassau). There the basis is blackish-gray; the 

 crystals of labradorite grayish white, and scarcely translu- 

 cent; the crystals of augite are blackish-green, with a con- 

 choidal fracture. The acicular porphyry of South Norway 

 belongs to this variety ; it has been described by Von 

 Buch« Porphyry, containing augite as its principal ele- 

 ment, is met with at Nicolajewsk, near Miask, and Nischne 

 Tagilsk. 



There the augite is large, and grass-green ; the crystals are 

 easily removed from the basis, and leave their impression. 



