QUE What is the difference between crystalline silica (quartz) and amorphous silica (quartz glass)?

 Crystalline Silica (Quartz ) 

1 it is crystalline compound.

2 it exist in regular tetrahedron in which SiO42-  is present at corners. Each corner is shared by others results into network solid.

3 it has sharp melting point.

 

Amorphous Silica (Quartz Glass)

1 it is amorphous compound.

2 it also have SiO42- at the corners of tetrahedron but they are randomly shared by others results into polymeric form or 3D network structure.

3 it does not have sharp melting