The context and details of the clast in Figures 5(F) and 7(A) within a heterogeneous mass of pseudomorphed volcanoclastic material and carbonaceous matter (CM). (A), (B) Plane and polarized light micrographs of the sediment showing the location of the target clast (red arrows). (C), (D) Plane and polarized micrograph details of the target clast illustrating its rectangular, block form, suggestive of perhaps a feldspathic protolith (outlined by the dotted red line). Note the microcrystalline nature of the quartz matrix and protolith replacement.