431 
Geology of the Environs of Petersburg. 
Red felspar , thickly spotted with hornblende. A handsome stone. 
In situ ; Borgo, in Finland. 
Rolled ; Moscow road, one verst from Petersburg. 
Dark granite, with iridescent felspar. When the felspar is well 
crystallized, the colours range themselves round the edges of it, if cut 
transversely : the blue in the centre, the green and yellow round it. 
In situ ; unknown. That of Norway is of a whiter colour. 
Rolled ; Peterhof. 
Black mica slate , with crystals of staurolite — rare. 
In situ ; said to be so near Cuopio in Finland. 
Rolled ; near the Moscow gate. 
Hornstone , or coarse jasper, red clouded with yellow. 
In situ ; unknown. 
Rolled ; I have seen only one large block on the shore close to the 
summer-house at Becova. 
Basalt. 
In situ ; said to be in the north of Finland, Lapland, and 
Norway. 
Rolled ; one small fragment of a pillar was found on the 
Moscow road, and is in the cabinet of the Mineralogical Society at 
Petersburg. 
Secondary Rocks. 
Limestone of the country; sparingly; only the hardest varieties, 
and never far from the same stratum in situ. 
Sandstone of the intermediate bed ; very sparingly, in various 
parts of the country, and only the hardest sorts. 
Vol. V. 3 i 
