Mihajlovic T , Lengauer C L , Ntaflos T , Lolitsch U , Tillmanns E , Neues Jahrbuch fur Mineralogie, Abhandlungen , 179 (2004) p.265-294, Two new minerals, rondorfite, Ca8Mg[SiO4]4Cl2, and almarudite,, K(box,Na)2(Mn,Fe,Mg)2(Be,Al)3[Si12O30], and a study of iron-rich wadalite,, Ca12[(Al8Si4Fe2)O32]C16, from the Bellerberg (Bellberg) volcano, Eifel, Germany, Locality: Bellerberg volcano lava field, 2 km N of Mayen,, Eastern Eifel volcanic area, Eifel, Germany