Sillimanite minerals are mainly utilised in the production of mullite or high-alumina refractories. 95% of the world’s consumption of these minerals is used for this purpose in the manufacture of metals, glass, ceramics and cement.
A common form of Sillimanite is known as fibrolite. It is named fibrolite because the minerals occur like a bunch of fiber twisted together when observed in thin sections or by naked eyes. Both the fibrous and common forms of traditional Sillimanite are found in metamorphosed sedimentary rocks.