THE GEMSTONE LIBRARY
Tetraferriphlogopite
Tetraferriphlogopite belongs to the mica family. Its long name tells a structural story: ferric iron occupies a position in the silicate sheets that aluminum fills in ordinary phlogopite.
What is it?
Tetraferriphlogopite is a recognized mineral species in the biotite group of micas, with the ideal formula KMg3(Si3Fe3+)O10(OH)2. The “tetraferri” part refers to iron in the tetrahedral sheet, not a claim that the specimen contains four separate kinds of iron. The modern mineral name has no hyphen; older literature may call it “tetra-ferriphlogopite.”
A mineral of layers
Like other micas, its crystal structure is built from stacked silicate sheets, which can part along the layers. Scientists have examined natural Tetraferriphlogopite from carbonatite-related rocks in Brazil and elsewhere. Those studied occurrences explain the mineral, but do not establish a locality for our pictured material.
About this collection
Our February 2026 material was supplied as Tetraferriphlogopite. We have not published a specimen-specific laboratory identification or verified a mine of origin for the pictured piece. Similar-looking micas require analytical work to distinguish, especially when the distinction rests on where iron sits in the structure.
Care
Protect the edges and layered surfaces from rubbing or knocks. Dust gently with a soft, dry brush and store the specimen separately from harder stones.
Sources
- International Mineralogical Association CNMNC · Official mineral list and nomenclature
- Clays and Clay Minerals · Crystal chemistry of natural Tetraferriphlogopite and phlogopite
These references describe the mineral species and studied samples; neither is an analysis of the photographed Soul Body Gems piece.