Aragonitic coated grains < 1 mm in diameter with a layered cortex formed by crystals of tangential orientation are characteristic of ooids from the Bahamas (Illing 1954, Newell et al. 1960). This structure is normal for recent ooids from marine environments (for exceptions see Land et al. 1979). The µm-sized aragonite crystals are rod- or baton-shaped (Fabricius and Klingele 1970, Loreau 1970).