Nierite

A species of Minerals

Silicon nitride is a chemical compound of the elements silicon and nitrogen. Si3N4 is the most thermodynamically stable of the silicon nitrides. Hence, Si3N4 is the most commercially important of the silicon nitrides when referring to the term "silicon nitride". It is a white, high-melting-point solid that is relatively chemically inert, being attacked by dilute HF and hot H2SO4. It is very hard (8.5 on the mohs scale). It has a high thermal stability.

Hardness:

9

Density:

3.11 g/cm³