Abstract: This invention relates to reusable crucibles for production of ingots of semiconductor grade silicon made of nitride bonded silicon nitride (NBSN). The crucibles may be made by mixing silicon nitride powder with silicon powder, forming a green body of the crucible, and then heating the green body in an atmosphere containing nitrogen such that the silicon powder is nitrided forming the NBSN-crucible. Alternatively the crucibles may assembled by plate elements of NBSN-material that are to be the bottom and walls of a square cross-section crucible, and optionally sealing the joints by applying a paste comprising silicon powder and optionally silicon nitride particles, followed by a second heat treatment in a nitrogen atmosphere.