Tungsten mine in Mosedale: high melting point

 

There's a display board appeared at the mine in Mosedale since I last visited. Tungsten used to be a well-known element because it was used for the filaments in light bulbs. This was because the melting point was so high. That leads me to ask the obvious question: why does tungsten have such a high melting point? I don't know enough about solid state physics to really understand this but I am interested that increased shielding increases the melting point. I do teach that more shielding means more reactive because the nucleus is less likely to hold onto outer electrons and thus lose them to form positive ions. But here maybe it is the losing of electrons that leads to more metallic bonding. Maybe all will become clear with more solid state knowledge.