The transparent form of cordierite, Iolite is a magnesium iron aluminum cyclosilicate mineral. While this mineral’s history travels a long way back, Iolite is comparatively modern and not very popular. The crystal derived its name from a Greek word ‘Ios’, which means ‘violet.’ It also had a trade name ‘water-sapphire’, because of its strong pleochroism, however, the name today has become obsolete. The gemstone can appear sapphire from one side and can give a clear water-like appearance from another. Additionally, it can also display honey-yellow or light green color from the top.
Another name for Iolite is ‘Dichroite’, which denotes its pleochroic feature. Dichroite comes from the Greek word meaning ‘two-colored rock’
Mineral Family- Cordierite
Refractive Index– nα = 1.527 – 1.560 nβ = 1.532 – 1.574 nγ = 1.538 – 1.578 Indices increase with Fe content.
Color- Blue, Bluish violet, Yellowish brown, smoky blue, gray, brown, colorless pale, blue, greenish
Deposits- India, Brazil, Canada, Myanmar, Madagascar, Sri Lanka, and Tanzania