Nifontovite

Unknown Owner

A wonderful cabinet sized example for this rare borate mineral. Many glassy gem crystals measuring as large as 3.5 cm in length are set nicely on matrix. Very slight damage present typical of these, this one is in particularly good condition. Specimens of the species from this locality easily rank as the world's finest. Charcas is a historic mining district located in the central part of the San Luis Potosi state, Mexico, situated within the Mesa Central geomorphic province. Geologically, it is a world-class skarn deposit formed by the intrusion of Eocene-aged granodioritic stocks into a sequence of Jurassic and Cretaceous limestones and shales. This intense contact metamorphism resulted in massive replacement bodies rich in zinc, lead, and silver, along with a complex suite of calcium silicate minerals. Historically, mining in Charcas began in the late 1500s following the Spanish conquest and has remained an active industrial center for over four centuries. The district is particularly famous for its spectacular fishtail twin calcite and danburite specimens, which are found in large hydrothermal pockets within the skarn zones. While the district is a classic for Mexican minerals, it has recently gained international attention for extraordinary finds of nifontovite. Nifontovite is a rare hydrated calcium borate mineral that typically occurs as colorless to white glassy crystals. The recent Charcas specimens are considered the finest ever discovered, featuring large, transparent, and highly lustrous monoclinic prisms that far surpass previous occurrences in Russia or Japan. These fantastic crystals are found in hydrothermal pockets, often associated with danburite and datolite, and represent a significant milestone in mineralogy due to their incredible size and gem-like clarity.