Iolite
What is Iolite?
Iolite is a transparent, violet-blue, light blue, or yellow-gray mineral. It’s primarily found in Sri Lanka, India, and Madagascar. Iolite is often used as a gemstone and is popular for its pleochroic property, showing different colors when viewed from different angles.
Iolite is a captivating gemstone that comes in shades of violet-blue to light blue. Its unique pleochroic property makes it a popular choice for jewelry like rings and pendants, as it shows different colors depending on the angle of view.
| Chemical Classification | Inorganic - Silicate |
| Color | Typically blue to violet, but can show yellowish-gray or honey color from different angles due to its pleochroism. |
| Streak | Blue |
| Luster | Vitreous. |
| Transparency | Transparent to translucent. |
| Occurrence | India, Sri Lanka, and Madagascar. |
| Formation | Formed under high temperature and pressure conditions in regional metamorphic rocks. |
| Diaphaneity | Transparent |
| Cleavage | Perfect in one direction |
| Mohs Hardness | 7 - 7.5. |
| Specific Gravity | Approximately 2.58 - 2.66. |
| Diagnostic Properties | Pleochroism (different colors when viewed from different angles). |
| Chemical Composition | (Mg,Fe)2Al4Si5O18 |
| Pleochroism | Strong; shows different colors when viewed from different angles. |
| Crystal System | Orthorhombic (variety of Cordierite) |
| Optical Properties | Biaxial (-) |
| Refractive Index | 1.522 - 1.578 |
| Birefringence | 0.008 - 0.012 |
| 2V angle | Measured: 78° to 82° |
| Dispersion | 0.008 - 0.012. |