It has been named in 1797, after the Molina de Aragón municipality in Spain. Beside its massive look, it may have columnar, fibrous, spiky, speleothem or other shapes. From its striped, patterned, colorful massive varieties ornamental pieces, animal figures etc. are polished. They are often named as ’onyx-marble’, but the real onyx is an usually black, greyish, whitish, striped, stained quartz variety. It can be found in sedimentary, metamorphic rocks, in hydrothermal veins, near warm wells and in limestone caves. After calcite, it is the most common carbonate mineral. Usually the shells of molluscs (snails, seashells etc.) and the material of pearls and corals are consist of aragonite. It has a lot of localities worldwide. Nice crystals of it turns up from Morocco, Spain, Australia etc.