OP STRATA. 



37 



are sufficiently homogeneous and uniform to receive a polish. 

 Slaty ^ when the rock is in slaty tables or laminae, with trans- 

 verse veins of calcareous spar. This rock is often cut into 

 very small irregular blocks by the spar, which gives it the 

 name of checkered rock. 



Localities. Compact, about New-Lebanon Springs. Sla- 

 ty^ three miles south of the springs on the Hudson turnpike. 

 Variety. Checquered rock, on the Little Hoosick, and near 

 New-Lebanon Springs. Contents. Chlorite and Calc, spar, 

 every where. 



10. Calciferous Sandrock, consists of fine grains of 

 quartzose sand and of carbonate of lime, united without ce- 

 ment, or with an exceeding small proportion. Subdivisions. 

 Compact, when the rock is uniform, or nearly so, without 

 cells or cavities. Geodiferous, when it contains numerous 

 geodes, or curvilinear cavities ; which are empty or filled 

 with calc. spar, quartz crystals, barytes, anthracite, or other 

 mineral substances different from the rock. Varieties. 

 Oolitic, when it consists in part of oolite, of a dark colour, 

 and harder than the kind which is common in the lias or ooli- 

 tic formation of Europe, New-Jersey and Ohio. 



Localities, Compact, Flint Hill. Geodiferous, at Flat 

 Creek, west of the Noses. Varieties. Oolitic, near Sarato- 

 ga Springs. Sparry, at Flat Creek. Quartzose, on the 

 north side of the Mohawk, opposite Flat Creek. Contents. 

 Concentric concretions, near Saratoga Springs. Sulphate of 

 barytes and anthracite, on the West Canada Creek, six miles 

 above its mouth, also at Little Falls. Semi-opal, connected 

 with the quartzose variety. Brown spar and Hornstone, at 

 Flint Hill. Coarse agate in large quantities, and fine fortifi- 

 cation agate in small quantities at Flint Hill, and in the north 

 hill opposite Spraker's Basin on the Mohawk. Also numer- 

 ous quartz crystals with pyramids at each end and containing ^^thrac 

 anthracite, in the same locality and near Rensselaer School in ^" ^^^^^^ 

 Troy. In some, anthracite is seen, floating in a limpid liquid. 



