Chloridophlogopite

Chloridophlogopite is a mineral belonging to the mica group. It is a trioctahedral phyllosilicate mineral with the chemical formula KMg3(AlSi3O10)(Cl,OH)2. This formula indicates that it is a potassium, magnesium, aluminum, silicon, oxygen, and chlorine/hydroxyl compound. Chloridophlogopite is a variety of phlogopite where chloride ions have substituted for hydroxyl ions in the crystal structure. It typically forms in metamorphic rocks, particularly in schists and marbles that have undergone metasomatism. The mineral is characterized by its flaky or tabular habit and its monoclinic crystal system. It exhibits a pale brown to yellowish-brown color. Chloridophlogopite is relatively soft, with a Mohs hardness of around 2.5 to 3. It has a specific gravity of approximately 2.8. Its cleavage is perfect parallel to the {001} plane, which is characteristic of all micas, allowing it to be easily split into thin sheets. The presence of chlorine distinguishes it from the more common end-member phlogopite, which contains only hydroxyl groups. It is found in various geological settings worldwide, often associated with other magnesium-rich silicate minerals.