Pitchstone, a low grade variation of obsidian, often appearing a dull black or grey colour. These specimens come from Turkey and are available in various optional sizes.
Pitchstone is a glassy rock similar in appearance to obsidian but with a duller colouration. Like obsidian, it is formed by volcanic activity when lava makes contact with water. It is suggested pitchstone forms with higher water content than obsidian, this results in it not having a conchoidal fracture like obsidian, and is more blocky. Well known locations of pitchstone in the UK include the Isle of Arran and An Sgùrr, Eigg, Scotland. These particular samples come from Turkey and are limited.