Clinohumite is a gemstone quality magnesium silicate with a chemical formula distinguished by silicate and oxide layers. It is an extremely rare mineral and an especially rare gemstone. Clinohumite is a member of the humite group of minerals, which also includes humite, norbergite and chondrodite. Of the humite group, only chondrodite and clinohumite are known to produce gemstone quality deposits. The humite group of minerals was named after Sir Abraham Hume (1749-1838). Hume was a very well-respected English mineralogist, as well as a renowned collector of fine art.Clinohumite was first discovered in 1876. Until recently, it was thought to be one of the ten rarest gemstones in the world, with only a few thousand carats worth of gemstones known to exist in private collections. The first specimens of clinohumite were discovered in limestone blocks that had erupted from Mount Vesuvius near Naples, Italy. Later, more deposits of clinohumite were discovered in the Pamir Mountains during the early 1980s, and in the early 2000s, another deposit was found in the Taymyr Peninsula in the Far North of Russia. The most recent find was discovered in the Mahenge Plateau in the Ulanga District of the Morogoro Region of Tanzania, Africa in 2005.