Final answer:
Igneous rocks, specifically the plutonic or intrusive type, are most susceptible to hydrolysis due to their high silicate mineral content which reacts with water.
Step-by-step explanation:
The type of rocks most susceptible to hydrolysis are those high in silicate minerals, such as igneous rocks, particularly the plutonic (or intrusive) variety. Hydrolysis is a chemical weathering process involving water that can alter rocks by breaking down minerals and changing their composition. Plutonic rocks form deep within the Earth's crust from slowly cooling magma, which allows large crystals of silicate minerals to form. These minerals, including feldspars and micas, are particularly reactive with water during hydrolysis, leading to the breakdown of rock and the formation of clay minerals and dissolved ions.
On the other hand, metamorphic rocks can also be susceptible to hydrolysis, especially if they contain silicate minerals that were present in their precursor igneous or sedimentary rocks. However, sedimentary rocks, which often consist of clastic material or carbonates, tend to be less reactive to hydrolysis compared to plutonic rocks. Unjointed rocks, regardless of type, may be less exposed to water infiltrating their structure, potentially slowing down the hydrolysis process.