MgAl₂O₄

This sample of spinel is displayed in the Smithsonian Museum of Natural History. Spinel is an oxide of magnesium and aluminum with the composition MgAl₂O₄ . This sample is about 8x8 cm and is from Antanimora, Madagascar.

This sample is spinel with calcite and is from Mogok, Burma. It is about 7x7 cm.

These spinel gems are 36.1 and 34.1 carats and are from Burma. "It is easy to confuse red spinels with rubies. They are found in similar places and have similar properties. The Black Prince Ruby in the British Crown Jewels is really a spinel! Impurities create many colors of spinel; red from chromium is the most prized."

These red spinel samples are from Mogok, Burma. The largest sample is about 3cm tall.

These spinel gems are 29.7, 22.2, 45.8 and 22.1 carats. They are from Sri Lanka.

At left is a bracelet with spinel crystals in it. It is from Burma.

The right sample of spinel is from Orange County, New York. It is formed with hornblende and measures about 5x5 cm.