Ferroindialite

ferroindialite

sillimanite

wagnerite

zircon

Images

Formula: (Fe²⁺,Mg)₂Al₄Si₅O₁₈
Cyclosilicate (ring silicate), hexagonal paramorph of orthorhombic sekaninaite
Crystal System: Hexagonal
Specific gravity: 2.66 measured, 2.667 calculated
Hardness: 7
Streak: White
Colour: Brownish violet to grey with violet-blue tint
Environments

Volcanic igneous environments

Localities

At the type locality, the Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany, ferroindialite was discovered in a xenolith rock amongst alkaline basalts, in association with sillimanite, sanidine, phlogopite, enstatite-ferrosilite, wagnerite, fluorapatite, tridymite, zircon and high-magnesium almandine. The ferroindialite forms short prismatic or tabular crystals up to 1.5 mm in size (AM 100.334-335).

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