Phlogopite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NamePhlogopite
Chemical FormulaKMg₃(AlSi₃O₁₀)(OH)₂
Mohs Hardness2.5
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect basal on {001}
Fractureuneven
Specific Gravity2.83
Colorsyellowish-brown, golden-brown
Transparencytranslucent
Type LocalitySan Vito quarry, San Vito, Ercolano, Monte Somma, Somma-Vesuvius Complex, Naples Province, Campania, Italy
Mineral GroupSilicates
Useselectrical insulation, filler, drilling muds, collector
Associated Mineralscalcite, dolomite, diopside, forsterite, apatite, magnetite
Raritycommon
Description
The image displays a translucent, yellowish-brown phlogopite crystal with a distinct platy, pseudo-hexagonal habit, embedded within a granular matrix of other minerals.
Geological Context
Phlogopite is a common mica found in magnesium-rich igneous rocks such as kimberlites and lamprophyres, and in metamorphic rocks like marbles and schists, often forming under high temperature and pressure conditions.
