About Unusual Cavities in the Limestone of Herkimer County, New York

Near Middleville, in Herkimer County, New York, in a calciferous limestone, gray and brownish-gray in color, there are numerous cavities varying in size from that of a pinhead to that of a man's head. In these cavities are found carbonaceous substances such as asphaltum and other hard, black hydrocarbons. These cavities also frequently show mud or sand adhering to the sides, or mud and sand mixed with the petroleum, in which are often found brilliant and transparent rock-crystals, the purest of any found in the world. They are unusually perfect hexagonal prisms with both sets of six pyramid faces; that is, with same slight modification, eighteen brilliantly polished faces. These are especially sought after on account of their great purity, and because it is considered that he who wears one will have fair weather and secure the blessing of fair sailing on the sea of life. Some of these crystals are so small, though of absolute perfection, that it would require 250,000 of them to weigh an ounce; others again are sometimes as large as from one to two inches in length. When not entirely transparent they frequently contain inclusions of black asphaltum or other hydrocarbons and also contain hollow cavities which are filled with fluid, sometimes salt water and sometimes liquid carbonic acid gas. In these are moving bubbles and occasionally a heavy hydrocarbon; that is, a bubble will ascend and the hydrocarbon will sink; or else the bubble will rise and take with it a small speck of hydrocarbon, and another will sink. In a wonderful specimen now at the American Museum of Natural History there is an object like a small spider of hydrocarbon which sinks while a minute water-bubble rises. They are called fair-weather stones.