Quartizite is metamorphosed from

Quartzite is the hard, non-foliated metamorphic rock produced by recrystallization of quartz-rich sandstone when exposed to high temperatures and pressures. During metamorphism the quartz grains in sandstone fuse and recrystallize into an interlocking quartz fabric, greatly increasing hardness and induration; thus sandstone is the protolith of quartzite [2]. Textbook lists of protolith–metamorphic rock pairs explicitly pair sandstone→quartzite while contrasting other transformations such as limestone→marble or shale→slate, confirming the correct source rock for quartzite [2]. This change happens in contact or regional metamorphic settings where heat, pressure, and fluids drive quartz recrystallization to form quartzite.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 13: Types of Rocks & Rock Cycle > Thermal Metamorphism > p. 173
2. [2] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 2: The Earth's Crust > METAMORPHIC ROCKS > p. 19