Structure of quartz (crystalline) and quartz glass (amorphous)

Quartz is a form of SiO2 (silica). It has tetrahedral SiO4 units which are orderly arranged in crystalline quartz as shown.
 In this arrangement, SiO4 tetrahedra are connected to one another such that oxygen atom of each SiO4 tetrahedral is shared with another atom. 

When SiO2 is melted and the melt is cooled, it forms quartz glass which is amorphous. In this state,  The SiO4 units are randomly joined. Thus, in quartz (crystalline),

SiO4 units are orderly arranged while in quartz glass (amorphous), the SiO4 units are randomly arranged. While the two structures are almost identical, yet in case of amorphous quartz glass there is no long range order.
 The structure of amorphous solids is similar to that of liquids.

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