Chalk and coal are examples of sedimentary rocks, but they are not the same type.

* Chalk is a type of biogenic sedimentary rock, formed from the accumulation of the skeletal remains of microscopic marine organisms called coccolithophores.

* Coal is a type of organic sedimentary rock, formed from the accumulation and compression of plant matter over millions of years.

So, while both chalk and coal are sedimentary rocks, they are formed from different materials and processes.