The gemstone variety of cordierite, an iolite is a mineral under the composition of magnesium aluminum silicate. As the transparent variety iolite, it is very much widely used as a precious stone. The name “iolite” is derived from the Greek word for violet. Dichroite is another old name that is still being termed for this variety at these times. It is a  Greek word which to a degree has a meaning of “two –colored rock,” which was such a character to the compound cordierite’s solid pleochroism.
The gemstone crystallizes in the orthorhombic system under the crystal crystallography and has crystals having transparent and translucent characteristics. The gemstone is typically blue, violet, gray, or of the brownish shade and color but is very much pleochroic, in which it transmits different colors when viewed in different axes and when being rotated can alter from the color blue –violet to the yellowish gray color. Iolite is also called as water sapphire or diochroite. Gem quality iolite typically varies in color formations from a sapphire blue to indigo to gray of a particular yellow shade, as stated, to light blue as the angle of the stroke of light changes.
The gemstone has hardness of not less than 7 but does not to exceed more than 7.5 on the Mohs scale and specifically has a relative density of 2.4 to 2.7. The stone has an uneven conchoidal or a shell–shaped fracture. Same as other gemstones of the same varieties, it has a glossy and a vitreous luster. Being distinguished by pleochroism, it can be resembled by quartz. It can also be distinguished from corundum by its lower hardness. Indialite, which is a polymorph of a high temperature exists, contains the same type of crystalline structure with beryl.
The gemstone particularly consists of an alumino silicate tetrahedral structure. The gemstones are made up of rings of six tetrahedrons in which the rings are being associated by magnesium atomic particles which are being chained to six oxygens. The rings are eventually aligned to build up big channels which go particularly through the framework. Such particular channels may be tied up by existing molecules such as carbon dioxide, methane, and even water. There is much substantial and large significant concentration in the exploration of the use of this particular component as a structure for catalytic converters and the potential cracking of the hydrocarbon compounds.
Naturally, iolite is of the property similar to shales, in which are fine–grained sedimentary rocks formed by the consolidation of layers of mud or clay. When being summed up neatly, many types of shale produce oil and the sedimentary rocks which contain huge amounts of oil that are named oil shales.
The best varieties of this gem quality stones are found mostly on Sri Lanka and most parts of India and South Asia, Burma, Brazil, the northern territories of Australia, the State of Connecticut in the U.S., Namibia, Tanzania, Madagascar, the Yellowknife area of the Northwest Territories of Canada, and in most parts of Africa.
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