pack of 20 haematite star beads
6mm across 
from google: haematite is one of the most abundant minerals on Earth's surface and in the shallow crust. It is an iron oxide with a chemical composition of Fe2O3. It is a common rock-forming mineral found in sedimentary, metamorphic, and igneous rocks at locations throughout the world. Hematite is the most important ore of iron.
These are heavier than they look to be :-)