Oltu stone aka black amber, a kind of jet

Oltu stone (Turkish: Oltu taßı) is a kind of jet found in the region around Oltu town within Erzurum Province, eastern Turkey. The organic substance is used as semi-precious gemstone in manufacturing jewellery. Location and extraction Oltu stone, sometimes called…

Jet

Jet is a type of lignite, the lowest rank of coal, and is a gemstone. Unlike many gemstones, jet is not a mineral, but is rather a mineraloid. It is derived from wood that has changed under extreme pressure. The…

Wood Opal

Wood opal is a form of petrified wood which has developed an opalescent sheen or, more rarely, where the wood has been completely replaced by opal. Other names for this opalized sheen-like wood are opalized…

Petrified Wood

Petrified wood, also known as petrified tree (from Ancient Greek πέτρα meaning ‘rock’ or ‘stone’; literally ‘wood turned into stone’), is the name given to a special type of fossilized wood, the fossilized remains of terrestrial vegetation. Petrifaction is the result…