Authigenic Feldspar in Limestone at Glens Falls, New York

Abstract

Introduction Small quarries on both sides of the Hudson at Glens Falls, New York, are producing stone for lime-burning from beds of Trenton limestone that are 15 feet thick and that dip gently to the south. The lime enjoys an almost exclusive market for use in drawing steel wire because of its freedom from constituents that scratch the wire. A microscopic examination of the insoluble residue of a sample of the limestone showed that it contains many completely developed crystals of albitic feldspar of authigenic origin. Character of the Limestone The limestone is a dark gray to nearly black crystalline-looking rock, which in thin-section is seen to consist of clouded aggregates of very finely crystalline calcite in a matrix of more coarsely crystalline calcite. The clouded aggregates are more or less spherical and have a microcrystalline and cryptocrystalline texture. Their dark color is due to an abundance of minute inclusions . . .