Sieleckiite is a rare mineral that occurs as a secondary mineral in oxidized copper deposits. Its name derives from the Polish mineralogist Zdisław Sielecki who first identified and described the mineral. It possesses a chemical formula of Cu3MoO4(OH)4, meaning it consists of copper, molybdenum, oxygen, and hydroxide ions.
In terms of physical properties, sieleckiite typically forms as small, acicular (needle-like) or prismatic crystals. It exhibits a vitreous to adamantine luster and ranges in color from a pale green or blue-green to a deep green shade. Its streak is light green, and it is non-fluorescent.
Sieleckiite is composed of layers of edge-sharing CuO6 octahedra that are bridged by MoO4(OH)2 tetrahedra, resulting in a complex crystal structure. It belongs to the orthorhombic crystal system and possesses an uneven fracture.
This mineral is primarily found in the oxidation zones of copper deposits associated with molybdenum-bearing ores. Its occurrence is quite rare and limited to a few locations worldwide, including the United States, Peru, and Russia.
While sieleckiite does not hold significant economic importance itself, its presence can indicate the potential for other valuable minerals within its associated deposit. The study and identification of sieleckiite contribute to understanding the geological processes that occur in copper-molybdenum-bearing ore systems.
