Metakaolin is a fine, white powder made by heating kaolin, a type of clay, to high temperatures. This process removes water and transforms the clay into a more reactive form, making it useful in various applications, particularly in the construction industry. In concrete and cement production, metakaolin acts as a pozzolanic material, which means it can react with calcium hydroxide to form additional cementitious compounds. This enhances the strength and durability of concrete, making it a popular additive for improving the performance of building materials.