Tetraferriphlogopite
Image: <a href="//commons.wikimedia.org/wiki/User:Kallerna" title="User:Kallerna">kallerna</a> (CC BY-SA 4.0)
Mineral NameTetraferriphlogopite
Chemical FormulaKMg3(Fe3+Si3O10)(OH)2
Mohs Hardness2.5
Crystal Systemmonoclinic
Lusterpearly
Streak Colorwhite
Cleavageperfect basal on {001}
Fractureuneven
Specific Gravity2.8
Colorsbrown, reddish-brown, yellowish-brown, green, black
Transparencytransparent
Type LocalitySiilinjärvi carbonatite, Finland
Mineral Groupsilicates
Usesgeological studies, scientific research
Associated Mineralsapatite, calcite, dolomite, pyroxenes, amphiboles
Rarityuncommon
Description
This image displays a thin section of rock under crossed polarized light, revealing a mosaic of mineral grains. The dominant tetraferriphlogopite exhibits vibrant, high-order interference colors (greens, yellows, reds, blues) and often shows characteristic mica cleavage, intergrown with other minerals that display lower birefringence.
Geological Context
Tetraferriphlogopite is a characteristic mica found in alkaline igneous rocks, particularly carbonatites, where it forms during magmatic crystallization or later metasomatic alteration. The Siilinjärvi carbonatite is a Precambrian intrusion known for its significant apatite mineralization.
