Blue mineral is a term used to describe a variety of minerals that have a blue hue. The five most common blue minerals are LAPIS, azurite, TALC, ALKALI, and OPAL. LAPIS is a deep blue metamorphic rock composed of several minerals, including lazurite, calcite, and pyrite. Azurite is a soft, deep blue copper mineral that is often found in association with malachite. TALC is a soft, white mineral composed of hydrated magnesium silicate. ALKALI is a group of minerals that contain sodium and potassium and are usually colorless or white. OPAL is a hydrated amorphous form of silica that can display a range of colors, including blue. Lastly, iolite is a transparent gemstone that ranges from light blue to violet in color.