Iolite
Iolite is a variety of the mineral Cordierite. It is a magnesium aluminium silicate and there is almost always a presence of iron within
the crystal.
The stone is violet blue in colour and displays an optical property called pleochroism - showing a different colour or depth of colour,
when viewed in different directions. Iolite has very strong pleochroism with differing colours of yellow, dark purple-blue and pale blue.
The stone has a hardness of 7.0 – 7.5 on the Mohs' scale, so is durable for jewellery but is a difficult stone to cut due to its colour
variations. The cutter has to ensure that the best colour of iolite is seen from the top of the stone.
Iolite is found in igneous rocks and pegmatite intrusions with its main deposits in Burma, Brazil, Sri Lanka, India and Madagascar.
The name ‘Iolite’ comes from the Greek ‘ios’ meaning violet. An alternative name for the stone is dichroite, which is Greek for ‘two-coloured
rock’ referring to its pleochroism. Iolite has been likened to light blue sapphires and is sometimes nicknamed ‘water sapphire.’
Iolite has been referred to as the Viking compass. When Leif Eriksson and other Viking explorers set out into the Atlantic Ocean, thin pieces
of iolite were used as a the first polarizing filter. Looking through the lens, they were able to determine the exact position of the sun, even
on cloudy days and in turn were able to navigate their way safely on the seas.