is a rare mineral of the eudialyte group with the formula Na27K8Ca12Fe3Zr6Si4[Si3O9]4[Si9O27]4(O,OH,H2O)6Cl2. Its structure is modular. It is only the third member of the group after andrianovite and davinciite with essential (site-dominating) potassium. Potassium and sodium enter both N4 and M2 sites. The mineral is named after Russian crystallographer Ramiza K. Rastsvetaeva.( from Wikipedia).
The hardness is the same as the Eudialyte: 5-6.
Translucent with fractures.
It comes from Kola, Khibiny massif, Mt. Rasvumchorr.
Size: 7.5x6.5x4 mm.