The Guanajuato silver mining district in Mexico is one of the most famous in the whole world. At its height, in the late 18th century, it was the world's leading silver producer with one mine - Valenciana mine - producing almost a third of the world's supply. Remarkably, this district is still mining to this day, showing an amazing longevity. Proustite, silver arsenic sulphide, is one of the most collectible of silver ore minerals owing to its wonderful blood-red internal reflections, and rarity in good crystals. This miniature Proustite is a real rarity for Guanajuato and displays nice crystallized surface features, with stepped growth lines. The back of the specimen is a slightly hollowed rough surface, where it was previously attached to matrix, but the front faces are all nicely crystallized. Although, it does not show the classic 'pointed' crystal form of terminated Proustite crystals, it is nevertheless a significantly large crystallized Proustite from anywhere in the world, but particularly for such a historically important silver mining region. There are some very tiny abrasions, but overall the crystal faces are intact and the flashes of red internal colour is lovely.