oolit

Oolit, also known as oölite or oölitic limestone, is a sedimentary rock composed of spherical or sub-spherical grains called ooids. These ooids typically range in size from 0.25 to 2 millimeters in diameter and are formed by the accretion of calcium carbonate around a nucleus, such as a grain of sand or a fossil fragment. The formation of ooids occurs in warm, shallow marine environments with agitated water, such as tidal flats or shoals, where the constant movement allows for the deposition of successive layers of calcium carbonate.

Oolitic limestone is often white, cream, or light brown in color. Its texture can vary depending on the size and packing of the ooids, ranging from fine-grained to coarser. Due to its characteristic appearance and ease of quarrying, oolitic limestone has been historically used as a building material. Notable examples of structures built with oolitic limestone include buildings in parts of England and the Great Pyramids of Giza in Egypt, although the composition of the latter is debated. In modern times, oolitic limestone is also used as aggregate in concrete, for decorative stone, and in some industrial applications. The presence and characteristics of ooids are a key indicator for geologists studying ancient depositional environments.