Iolite Vs. Sapphire

Iolite is a gemstone composed of magnesium aluminum silicate.^[1] Sapphire is a very popular gemstone and its chemical composition is silicon dioxide.^[2]

Quick Facts on Differences of Iolite and Sapphire

For a quick recap of the differences iolite and sapphire:

• While both iolite and sapphire can be translucent or transparent, sapphire can be opaque.
• In terms of crystallography, iolite is orthorhombic while sapphire can be hexagonal or trigonal.
• For chemical formulas, iolite is Mg2Al4Si5O18 while sapphire is Al2O3.
• While both iolite and sapphire is vitreous, in terms of luster, sapphire can be adamantine.
• While both iolite and sapphire can be commonly blue, iolite is often colorless and sapphire is often green.
• Iolite's hardness is lower than sapphire - iolite ranges from 7 to 7.5 and sapphire is 9 on the Moh's scale.
• Iolite's specific gravity is lower than sapphire - iolite ranges from 2.53 to 2.78 and sapphire ranges from 3.99 to 4.

Quick Facts on Similarities of Iolite and Sapphire

The similarities of iolite and sapphire include:

• Iolite and sapphire both streak colorless.
• Iolite's rarity is similar to sapphire.

Summary of Iolite

Iolite is a mineral that is also known as cordierite. It is a magnesium iron aluminum cyclosilicate that is found in metamorphic and igneous rocks. Iolite is typically blue to violet in color, but it can also be gray, yellow, green, or brown. It has a vitreous to dull luster and a Mohs hardness of 7 to 7.5.

Summary of Sapphire

Sapphire is a precious mineral that belongs to the corundum family. It is a variety of aluminum oxide that is distinguished by its blue color, although it can also be found in other colors such as pink, yellow, green, and purple. Sapphire is one of the hardest minerals in the world, with a hardness of 9 on the Mohs scale, making it an ideal material for use in jewelry and industrial applications.

Table Comparison of Iolite vs Sapphire