LIME. 



227 



^'«- ^°°- Schenectady County. About two miles north of the city, on the 



banks of the Mohawk, there is a stratum of gravel cemented by calcareous 

 spar, which has the form of an acute rhombohedron, the mixte of Haiiy. Fig. 

 100. sons 63° 44' 55"; sons' 116° 15' 5". The faces, however, are 

 sometimes a little rounded, and there is an approach to the metastatique of 

 Haiiy ; but this form is never well developed. This mineral has been called 

 arragonite ; in my opinion, incorrectly. 



Schoharie County. Interesting localities of calcareous spar occur in vari- 

 ous parts of this county. It has long been noted for the number of caverns 

 which it contains. These, as usual, abound in several varieties of carbonate of 

 lime, but they seldom furnish well defined or curious crystalline forms. There 

 are, however, several localities in various parts of the county, where crystals 

 of calcareous spar are found. These are generally in veins in the limestone, 

 or argillaceous limestone, which is here so abundant. Near Middleburgh, they are in the 

 form of the primary, with masses of anthracite occasionally running through them. About a 

 mile and a half east of the court-house, there is a vein ten or twelve inches in width, where 

 have been obtained crystals similar to Figs. 63 and 70, and nearly an inch in diameter ; and 

 there are several veins in the vicinity, where obtuse rhombohedrons occur. 



But the most interesting specimens of this mineral are those found on the banks of a small 

 stream which empties into the Cobleskill, four miles west of Schoharie court-house. At this 

 place there are, in a kind of water limestone, geodes of various sizes, sometimes a foot in 

 diameter, lined with crystals of calcareous spar, often forming specimens of great beauty. 

 The crystals are usually rhombohedrons, with the edges and angles truncated, and often 

 rounded in the manner already noticed under the head of Albany county, where similar spe- 

 cimens occur in the water limestone of the Helderberg. They are also sometimes in the 

 form of the metastatique of Haiiy ; and with all these, are intermixed delicate crystals of 

 strontianite of a white or yellowish white colour. Occasionally there occur at this locality 

 twin crystals of calcareous spar of a small size, some of which resemble those at Haverstraw 

 in Rockland county (Fig. 90), being formed from the union of two rhombohedra ; while there 

 is another, which is in the form of the double rhombic prism. 



The specimens of the calcareous spar from the various caverns, with which this county 

 abounds, should also be here noticed ; for although these do not often occur in regularly crys- 

 tallized forms, they can in most cases be easily reduced to the primary by cleavage. Of 

 these the most extensive is BalVs Cave, situated about four and a half miles northwest of 

 Schoharie court-house. This was first explored in September, 1831, by John Gebhard, Esq. 

 and other gentlemen. This cavern abounds in stalactites and stalagmites of great size and 

 beauty, with occasional crystals of the calcareous spar. The specimens are sometimes of 

 snowy whiteness, and often of a highly crystalline texture, although regular forms cannot be 

 observed. 



