kalterit
Kalterit is a rare and unusual mineral discovered in 1997. It is named after the German word "kalt," meaning cold, reflecting its low-temperature formation. Kalterit is typically found in low-temperature hydrothermal veins associated with granitic rocks. It is characterized by its distinctive blue color, which is due to the presence of copper in its crystal structure. The mineral has a hardness of 2.5 on the Mohs scale and a specific gravity of approximately 3.2. Kalterit is not commonly found in large quantities and is primarily of interest to mineralogists and collectors. Its formation and properties make it a subject of ongoing scientific study.