What has the density of 2.8?

A material with a density of 2.8 grams per cubic centimeter (g/cm³) is often found in certain types of minerals and metals. For example, aluminum oxide (corundum) has a density close to this value. Additionally, some gemstones, like sapphire and ruby, also exhibit similar densities. This density indicates that the substance is relatively heavy for its volume compared to common materials like water (1 g/cm³).