cordieriiti

Cordierite is a magnesium iron aluminum cyclosilicate mineral. It is known for its hardness and resistance to heat and chemical corrosion. The mineral's chemical formula is (Mg,Fe)2Al4Si5O18. Cordierite typically forms in metamorphic rocks that have undergone moderate to high-grade metamorphism, often in areas rich in aluminum and magnesium. It can also occur in some igneous rocks, particularly those that have undergone assimilation of surrounding metamorphic rocks.

The color of cordierite can vary, commonly appearing as grayish-blue, purplish, or yellowish-brown. In its purest form, it is colorless, but impurities often impart the characteristic hues. A notable variety of cordierite is known as iolite, which exhibits pleochroism, meaning it displays different colors when viewed from different angles. This optical property has led to its use as a gemstone.

Cordierite's properties make it valuable in industrial applications. Its low thermal expansion and high heat resistance make it suitable for use in ceramics, such as kiln furniture, cookware, and catalytic converter substrates. It is also used in the production of refractory materials and as an aggregate in lightweight concrete. The mineral is relatively uncommon and is found in various locations worldwide, including Scandinavia, India, and the United States.