Minerals identify

Know how to recognize them

Oneillite

Silicate mineral

Oneillite is a rare mineral of the eudialyte group with the formula Na15Ca3Mn3Fe2+3Zr3NbSiO(Si3O9)2(Si9O27)2(O,OH,H2O)3(OH,Cl)2. The formula is based on the original one but extended to show the presence of cyclic silicate groups and domination of Si at the M4 site. The mineral has lowered symmetry (space group R3, instead of more specific for the group R3m one) due to Ca-Mn ordering. Similar feature is displayed by some other eudialyte-group members: aqualite , labyrinthite Oneillite is strongly enriched in rare earth elements), but REE do not dominate any of its sites.

Identification

Color of mineral

Brown
Yellow

Mohs scale ( mineral hardness )

5
6

Density ( specific gravity )

1.65
1.64

Luster ( interacts light )

Vitreous

Crystal ( diaphaneity )

Trigonal