An amorphous iron-rich mineral occurring as reddish- or yellowish-brown masses in phosphatic sedimentary rocks.
Richellite is a hydrated phosphate and hydroxide of calcium and iron(iii) with fluorine, Ca₃Fe3+ ₁₀[(OH, F)₃| (PO₄)₂]₄. Crystal system: amorphous or (on heating) tetragonal.
Late 19th century; earliest use found in American Journal of Science. From French richellite from Richelle, the name of a locality near Visé in Belgium, where the mineral was discovered + -ite.