Lolite :

Lolite is a magnesium iron aluminium cyclosilicate. Iron is almost always present and a solid solution exists between Mg-rich cordierite and Fe-rich sekaninaite with a series formula:(Mg,Fe)2Al3(Si5AlO18) to (Fe,Mg)2Al3(Si5AlO18). A high temperature polymorph exists, indialite, which is isostructural with beryl and has a random distribution of Al in the (Si,Al)6O18 rings.

Catalytic converters are commonly made from ceramics containing a large proportion of cordierite. The manufacturing process deliberately aligns the cordierite crystals to make use of the very low thermal expansion seen for one axis. This prevents thermal shock cracking from taking place when the catalytic converter is used.

As the transparent variety iolite, it is often used as a gemstone.The name "iolite" comes from the Greek word for violet.Another old name is dichroite, a Greek word meaning "two-colored rock",a reference to cordierite's strong pleochroism. Gem quality iolite varies in colour from sapphire blue to blue violet to yellowish gray to light blue as the light angle changes. Iolite is found in Sri Lanka, Burma, Australia's Northern Territory, Namibia, Brazil, Tanzania, Madagascar, Connecticut, and the Yellowknife area of the Northwest Territories of Canada.