The Sillimanite, also known as fibrolite is a stone that makes you feel delightful and fortunate to be alive. Sillimanite is highly exceptional and is found in two forms to include clear and glassy, or silky, and fibrous. In the fibrous form, the crystals are long slender prisms that look like fiber due to which is also known as fibrolite. The glassy stones are the ones that are used for making gemstones in jewellery because of their beautiful appearance. The sillimanite crystal is mostly available in the colour of green, but can also be in yellow, blue, white, or brown. The sillimanite hardness ranges from 6-7 making the stone difficult to cut.
Sillimanite is one of the three polymorphs with the formula Al2SiO5 (other two being kyanite and andalusite). Sillimanite crystallizes in the orthorhombic system. Most often, it is a fibrous mineral, sometimes with radiating crystal sprays. Less often, it is columnar, massive or compact. Prismatic crystals are very rare. The fibrous character is so well developed that a sillimanite variety is called fibrolite, which resembles a group of fibers twisted together.