52 
[Assembly 
they are not nearly so common as in the counties before mentioned. 
Every where, however, the close connexion between the serpentine 
and augite or trap, is too clearly marked to be mistaken. 
Mica Slate — This rock, although it has a limited range in the State 
of New-York, is characterized here as elsewhere, by the occurrence 
of garnet, staurotide, &c. This is well exhibited in the eastern part 
of Dutchess county. 
Transition Argillite — This rock, which is so extensively distributed 
throughout the State, is exceedingly poor in minerals. It sometimes 
contains beds and veins of quartz striated or crystalline. Rarely the 
crystals are perfect and of considerable size. Perhaps the best speci- 
mens that have been found in this rock, are those obtained along the 
line of the Catskill and Canajoharie rail-road. The same rock fre- 
quently contains veins of fibrous and crystallized carbonate of lime, 
brown spar and earthy oxide of manganese. And these, together with 
occasional and thin seams of anthracite, and some scattered masses and 
crystals of iron pyrites, constitute nearly the entire mineralogy of this 
rock. It may be added that the mineralogical character of the grey- 
wacke is nearly the same. 
Sparry Limerock — In this rock, which is among the oldest of the 
blue limestones, and which is characterized by its colour, and by its be- 
ing traversed in all directions by narrow seams and veins of white cal- 
careous spar : several minerals are often observed. Among these 
may be noticed nests of quartz crystals and brown spar ; crystals of 
oxide of titanium and magnetic oxide of iron. Dark coloured horn- 
stone, is also common in some of the layers of this rock ; and iron py- 
rites, is often found in considerable abundance in it. 
Calciferous Sandrock, of Eaton. — This rock, as characterized by 
Prof. Eaton, is chiefly composed of quartzose sand, and carbonate of 
lime, and is widely distributed. It is abundantly supplied with quartz 
of several varieties. In a decomposed rock of this kind, are found the 
beautiful crystals of Herkimer county, while fine specimens of drusy 
quartz occur in the same rock, both here and in the more northern 
counties of the State. Hornstone, calcedony and agate, are also found 
in the same stratum ; as at Flint-Hill, in Montgomery county, and at 
Saratoga Springs. Sulphate of barytes, and anthracite in small quan- 
tities, are occasionally seen in it. 
