Nifontovite

specimen number:
2133230

location:
Fuka Mine, Okayama, Japan

description:
Colorless crystals of this rare borate on matrix.

The Fuka Mine, located in the Bicchu-cho area of Takahashi City within the Okayama Prefecture of Japan, is a world-class mineral locality situated inside a large limestone plateau. Geologically, the site is a remarkable example of a high-temperature skarn deposit, formed by the intrusion of quartz diorite into Paleozoic limestone during the Cretaceous period. This intense contact metamorphism created a rare suite of borate minerals, including some of the finest specimens of nifontovite ever recorded. Nifontovite is a hydrated calcium borate that typically occurs at this site as colorless to white, transparent, prismatic crystals found within cavities in the gehlenite-spurrite skarn. Historically, the mine has been operated since the mid-20th century primarily for the extraction of industrial minerals such as calcite and for specialized marble products. While the industrial operations continue today, Fuka remains a critically important site for research and systematic mineral collecting, as it is the type locality for several rare species and a premier source for high-quality borates.

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