75-year-old letter leads to discovery of one of Earth's rarest minerals in THIS country, not US, Russia, China, it is...

An age-old letter, stored in a government archive for 75 years, has led to the accidental rediscovery of humboldtine -- an extremely rare Earth mineral. The letter from 1949 was found during a 2023 digitisation project in Bavaria state of Germany. The writing directed curators to a shoebox containing long-forgotten lemon-yellow fragments. A team of the Bavarian State Office for the Environment confirmed that the fragments were in fact humboldtine -- a mineral so scarce that it has been discovered at only 30 locations around the world till date. The unusual discovery has doubled Germany's documented reserves of the said mineral.

What is humboldtine?
Humboldtine is an organic mineral -- a unique class where carbon, hydrogen, and oxygen are bound to metals within its crystal lattice. Its chemical formula combines iron with oxalate, bringing about a soft and yellow texture with a resinous sheen. Its formation is a natural geological occurrence, resulting from iron-rich rocks' interaction with specific natural acids under damp conditions, according to a study published in the journal Clays and Clay Minerals.

Why is the discovery significant?
The discovery in Germany is particularly significant as the fragments are much larger than the typical millimeter-scale ones found elsewhere in the world. But the exact conditions that led to their formation remain a mystery. Beyond its rarity, humboldtine is gaining attention for other reasons as well: Its iron oxalate composition makes it efficient at shuttling electrons, indicating potential of application in future green technologies. The discovery also highlights the importance of digitising historical collections as it can lead to more such finds.