This collection contains an extensive sample of mineral types from around the world. Minerals are formed in the earth through geological processes and gemstones are minerals which have been cut and polished for ornamental purposes.. There are several thousand different minerals and most of them are formed through combinations of just a small number of elements. National Museums Northern Ireland has an excellent collection of minerals, from local, national and international locations. Our collection is particularly rich in zeolites, minerals made from aluminium, oxygen and silicon, found in the basalt lavas of the Antrim hills.