In terms of geological time, Elba Island is young with variable topographical features. Highly variably sized sand grains originate from geological activity 50 million years ago. Clear transparent and cloudy grains are silica. The silica grains are quite hard with sharp angles, indicating that they have not been worn down by wave and wind action, a process that takes millions of years in geological time. Specks of black in quartz sand grains are pieces of hornblende (amphibole) phenocrysts of volcanic origin. A few biogenic grains of marine origin are also seen in Elba Island sand.