Large cut end piece with a rough back of diamond bearing Kimberlite from the Monastery Mine in South Africa. Monastery kimberlite mine is located in the eastern Free state province  It was discovered in early 1876 by a prospector but was mined before this by local Bashoto tribesman for ilmenite. Large scale mining commenced in 1899.. The Monastery kimberlite is a group I kimberlite pipe of about 0.8 ha in surface area, that intruded Karoo sedimentary rocks. It has been dated 88-90 Ma.