Carbon dioxide at normal pressure turns into a solid state at a temperature of 70 degrees Celsius and river sand melts

Carbon dioxide at normal pressure turns into a solid state at a temperature of 70 degrees Celsius and river sand melts at a temperature of 1700 degrees Celsius. What conclusions can be drawn about the structure of these substances in the solid state?

These properties of substances indicate that carbon dioxide has a molecular structure, and sand has an atomic crystal lattice. Substances of molecular structure have low melting and boiling points, are in standard conditions in gaseous liquid and solid states. Substances with a crystalline lattice structure, have high melting and boiling points, are in a solid state under standard conditions. They are hard, durable, practically insoluble.