Identify the series of geologic processes that can transform sandstone into quartzite

Its formed by extreme heat and pressure, and later a melting and cooling process.

Explanation:

Quartzite is formed when a quartz-rich sandstone is altered by great heat and pressure, causing the quartz grains to get together in an extremely strong crystalline network.

It's often formed at convergent plates when the necessary conditions are easily met. It is one of the most durable and tough rocks on earth.