Gemstone Glossary

Datolite

Datolite is quite a popular mineral among collectors. It occurs in white, colorless, yellowish, brown, green and (rarely) orange, reddish or gray. The name is derived from the Greek ‘Dateisthai’, meaning “To Divide” referring to the fact that the mineral crumbles quite easily.

First discovered in the Connecticut River valley, USA in 1806, occurrence of Datolite has been reported in Russia; the Lake Superior region of Michigan and Paterson, New Jersey, USA; Bancroft, Ontario, Canada; Charcas, Mexico; Schwarzwald, Germany, Africa and Norway.



Datolite is formed from Calcium Boron Silicate Hydroxide [CaBSiO4 (OH)]. It ranks 5 to 5.5 on the Moh’s Scale of Hardness with a Specific Gravity of 2.8 to 3.0. Datolite belongs to the Datolite/Gadolinite minerals group (named after its two most common members). Members of the group include: Datolite, Bakerite, Gadolinite, Hingganite, and a few other rare minerals. The minerals contain alternating borate and silicate that are connected to each other in a sheet like structure.

Datolite occurs in two distinct forms: as discrete, vitreous crystals and as massive nodules. The massive variety actually has a cauliflower-like surface, the form valued by collectors for its beauty as a lapidary material. Massive Datolite, colored by copper and other minerals, is found in size of up to 10 inches in diameter. Such nodules range from white to red, reddish-brown, and orange (the most valuable), and are usually cut as cabochons or sliced and polished for inlay-work. Pink Datolite is also called “Sugar Stone”.

Datolite is rarely found as a facetted gem. Fine facet material has been found in USA (Massachusset, New Jersey, Connecticut), Canada and Africa. Gems over 20 carats in weight are extremely rare.