Pinakiolite is a very rare magnesium, manganese borate, unique in the world to the Langban deposit in Sweden. This is a fine, very rich specimen of large, lustrous, deep reddish-black laths to 1.2 cm concentrated in parallel-growth on the front of the specimen. Pinakiolite grains are richly peppered on both the front and back of the piece. Ex. Mullane Collection.