Hello Josiah, you ask a very good question and one that a lot of scientists who study rocks and the Earth called geologists are interested in.

Quartz rock is made of silicon and oxygen atoms that are bonded really strongly to one another and therefore, it takes a really high temperature to make it melt. From a number of experiments that tried to answer your very question, scientists found that it takes a temperature of about 1670 °C (3038 °F) to melt quartz. To give you an idea, that's almost 200 °C higher than the temperature required to melt steel!

The reason the temperature to melt quartz is so high is the huge amount of energy stored in the bonds between atoms in quartz; it takes A LOT of energy to get those atoms to separate from one another and turn the quartz in a liquid. Thank you for your question!