The sequence of increasing grades of metamorphism of a mudstone (shale, claystone, or siltstone) parent rock (protolith) is: slate (lowest grade), phyllite, schist, gneiss (highest grade). 1. Describe the change in grain size from slate to schist
2. How does the texture of phyllite differ from that of schist?
3. Why do you think that the micas (lat minerals) in these rocks are all parallel, r nearly so, to one another?

The slate is hard and fine-grained rocks and has a salty cleavage that is caused by the growth of minerals due to the metamorphose of the grain ground rocks while schist is medium grade sheet-like grain rock.

Hence slate (lowest grade), phyllite, schist, gneiss (highest grade) rocks.

Learn more about the sequence of increasing grades of metamorphism.

the egg cell forms through 1) meiosis. prophase is a phase in both meiosis and mitosis. fertilization will happen a little later. mitosis happens in my toes while meiosis is for reproduction.