Mudstone is a sedimentary rock - Edexcel - GCSE Chemistry - Question 3 - 2018 - Paper 1

To form slate from mudstone, specific conditions of heat and pressure must be met. The mudstone needs to undergo regional metamorphism, which typically requires burial beneath layers of sediment, leading to increased pressure.

Additionally, the temperature must be elevated, generally between 200°C and 400°C, facilitating the recrystallization of minerals within the mudstone and transforming it into slate. This process also aligns the minerals creating a foliation texture characteristic of slate.