Merokrin

Merokrin is a rare aluminosilicate mineral first described from the Merokrin district. It forms under high-grade metamorphic conditions and in hydrothermal veins, often in association with quartz, calcite, and fluorite. The name derives from the locality.

Crystal structure and appearance: Merokrin crystallizes in the monoclinic system and typically occurs as short prisms or tabular crystals. It has a vitreous to pearly luster, a pale blue to green color, and is transparent to translucent. Hardness on the Mohs scale is about 5.5–6; specific gravity around 3.3; it shows imperfect cleavage.

Chemistry and classification: Merokrin is an aluminosilicate with a framework built from aluminum, silicon, and oxygen, with alkali metal cations such as sodium and calcium that can substitute for one another. Trace elements such as iron and magnesium and small amounts of fluorine may be present, giving variable color.

Occurrence and discovery: Type locality is the Merokrin Mine in the Central Metamorphic Belt, where specimens were first described in 1990. Since then, additional occurrences have been reported in nearby hydrothermal districts.

Economic and research significance: Although not a major ore, merokrin is of interest to mineralogists for its crystal structure and its relationship to related aluminosilicates. It is collected by mineral hobbyists and studied using X-ray diffraction, electron microprobe analyses, and Raman spectroscopy.