Cryolite with Siderite

specimen number:
1052731

location:
Ivigtut Mine, Arsuk Fjord, Sermersooq, Greenland

description:

A choice crystallized example for the species, crystals to 1.5 cm in size across the top of matrix with siderite. Slight damage present. The specimen comes with an antique label as shown at the end of the video. This label gives an original acquisition date for the specimen in 1909.

The Ivigtut cryolite deposit, located on the Arsuk Fjord in southwest Greenland, was a highly specialized open-pit mining operation that contained the world's only economically viable source of natural cryolite. Geologically, the deposit was a unique, highly fractionated granitic pegmatite-like stock that intruded Precambrian-age gneisses and granites during the Gardar rifting episode. This central body consisted of a massive, pure cryolite-siderite-quartz core containing abundant minor fluorides, sulfides, and specialized aluminofluoride minerals, which formed from late-stage fluorine-rich magmatic fluids trapped under a volcanic canopy. Historically, the local Inuit utilized the soft white mineral for weight and tobacco additives long before formal geological documentation by Europeans in the late eighteenth century. Commercial open-pit extraction began in 1854 under Danish concessionaires and expanded exponentially after the 1886 development of the Hall-Heroult process, which utilized molten cryolite as an essential flux to dissolve alumina in the industrial smelting of aluminum. The mine was operated heavily by the Kryolitselskabet Oresund company through the twentieth century, providing a critical strategic source of aluminum flux for the Allied powers during World War II before the natural ore body was completely exhausted and commercial open-pit extraction ceased in 1987. Since the shutdown, the flooded pit has remained inactive, though processing of remaining stockpiled low-grade tailings continued at secondary facilities for several years, and the historic site remains a landmark for geological study into 2026.

Dr. Ludwig Eger (active c. 1870-1915) was a highly respected Austrian mineral dealer based in Vienna who played a significant role in the distribution of Central European and Alpine mineral specimens during the late 19th and early 20th centuries. Operating under the firm name "Dr. L. Eger," his business was situated in the heart of Vienna, a primary hub for scientific exchange during the Austro-Hungarian Empire. Eger was noted for his professional, academic approach to the mineral trade, often supplying high-quality, systematic collections to universities and major museums throughout Europe and North America. His labels are easily recognized by their classic 19th-century typography, typically featuring "Dr. L. Eger, Wien" (the German name for Vienna) and providing detailed locality and species data in a formal, structured format. In addition to minerals, Eger dealt in paleontological and zoological specimens, as was common for the natural history establishments of the time.

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