No. 50.] 
245 
The red shale and slate, No. 5 of the above section, may perhaps, 
for economical purposes, be called a red marl. It contains some lime, 
and there are several thin bands of limestone. The whole of this stra- 
tum has the aspect and composition of the red marl rock of Rockland 
county, described in the third annual report. 
The pyritous slaty limestone lying next above, is more or less ar- 
gillaceous, and loaded v^^ith crystallized pyrites, v^hich are continually 
decomposing and forming gypsum. The mineral thus formed coats the 
rocks in brilliant druses or flocky and acicular efflorescences. Epsom 
salts are also formed, if the taste is to be trusted ; and Mr. Robinson 
the ovi^ner of the locality, says, that the saline matter sparkles or de- 
flagrates slightly when thrown on red hot coals. This sparkling would 
indicate the presence of nitrate of lime. 
I advised Mr. Robinson to grind some of the pyritous limestone and 
red marl, as they are easily crushed, and when spread on the ground 
and exposed to the weather, both would give rise to the formation of 
gypsum, by the decompositon of the pyrites and the combination of the 
sulphuric acid thus formed with the lime. The slaty limestone is rich 
in pyrites, minute crystals of which are disseminated through its mass ; 
and judging from the relative proportions of pyrites and limestone, it is 
supposed that this material, when ground or crushed might be worth as 
much for use as one half of its weight of pure gypsum. 
Should it ever be deemed expedient to work the stratum, numerous 
localities might be found in the vicinity. 
At Schoharie, near the bridge over the creek, the stratum containing 
the pyrites is exposed, underlying the Helderberg or Schoharie lime- 
stone series. This locality has been long known in consequence of 
the fine crystals and groups of crystals imbedded in the decomposed 
clayey green shale. 
Many places were observed, where the same crumbling green shale, 
interlaminated with limestone, and containing an abundance of pyrites, 
was underlying the Helderberg limestone series. The slate, or dark 
colored shale, which contains the fibrous sulphate of baryta, lies di- 
rectly below the pyritous rock in Carlisle and Sharon, in Schoharie 
county. 
