Spinel  is a very beautiful, attractive and traditionally important gemstone mineral. Spinel is the magnesium/ aluminium associate of the  greater spinel group of minerals. The Chemical formula of Spinel is MgAl2O4 in the cubical crystal system. The name Spinel comes from the Latin word “spinella”, that meant for its pointed crystals.

Physical Properties of Spinel:

            One property of spinel is that it crystallizes in the isometric. The most common crystal are formed in octahedral shapes, they are  typically paired. Spinel’s hardness is know to be 8, and it’s specific gravity is between 3.5-4.1. From transparent to opaque spinel has glassy to dull luster. Many spinel are known to be colorless, but you can usually see  numerous shades of red, rose, pink, green, blue, yellow, violet or black. Violet shade is very rare. It has measured density of 3.6 – 4.1 g/cm³ i.e and calculated is 3.578 g/cm³.

Spinel’s optical properties:

• Spinels are Isotropic in nature.
• There color/ Pleochronism is Non-pleochronic.
• Twinning is common.
• As they are Isotropic in nature therefore they have no birefringence.

It is a common metamorphic crystal found imbedded in crystalline limestone. It also occurs as an supplement mineral in many elementary rocks. It regularly made as a contact metamorphic crystal linked with mineral like graphite. They are often found as rolled pebbles in sands of streams, where it has been preserved because of its tough physical and chemical properties. One of the spinel like rubies are found in this way, frequently related with the gem corundum, in the sands of Srilanka, Upper Burma and Madagascar. Regular spinel is found in several areas of New York and New Jersey. In Canada, at Burgess, Ontario, and Wakefield, Quebec. The largest known spinel in the world is called the Samarian Spinel, that weighs 500 carats i.e. 100g. Some Spinel are the most eminent gemstones, one of them are the black prince’s ruby and the ‘Timur Ruby’ in the British Crown Jewels.