| Many of the grains are partially to entirely replaced by fine-grained sericite and quartz. |
| Sericite is fine-grained muscovite formed by alteration of such minerals as feldspar, cordierite, and sillimanite. |
| Subhedral plagioclase is slightly to extensively altered to saussurite and sericite. |
| There is some sericite present, also magnetite, resulting from the decomposition of the biotite. |
| These are actually pseudomorphs of sericite after cordierite and are found included in hornfels or slate as a product of contact metamorphism. |
| At some locations sericite completely pseudomorphs topaz and the feldspars. |
