Final answer:
Sandstone transforms into quartzite when subjected to intense heat and pressure, creating a dense, crystalline, and durable metamorphic rock.
Step-by-step explanation:
When sandstone, a clastic sedimentary rock composed of sand-sized minerals, rock fragments, or organic material, is subjected to intense heat and pressure, it metamorphoses into quartzite. This transformation occurs deep beneath Earth's surface, often several kilometers down where the pressure from overlying rocks and the heat from intrusions of molten rock are sufficient to recrystallize the sandstone's quartz grains into a dense, interlocking crystalline structure.
Quartzite is a hard, white metamorphic rock that is very resistant to weathering and erosion. It originates from the metamorphism of quartzose sandstones or siltstones and can retain the original texture of the sandstone with visible sand grains, or it can be composed entirely of interlocking quartz crystals. This rock is not reactive with dilute acid, differentiating it from other rocks like marble, and can be found in various colors depending on impurities present.