very hard to obtain these days, a rich specimen of Blackbird Mine ludlamite... a rarity from anywhere in fact with decent crystals. These crystals measure to 0.7 cm and are very sharp, which is what the locality was noted for.Most of these came out in the 1960s and the mine is long since closed. These remain rare, desired, US classics 5.2 x 3.4 x 0.6 cm