GTW10: Ancient stone.

Natural stone. Biomicritic limestone (wackestone for Dunham, 1962; Embry and Klovan, 1971), brown in plane-polarized light, containing planktonic foraminifera (Globigerinids and Globotruncanids) (from “Scaglia Rossa” formation) and rare opaques and iron hydroxides (pictures below, top left). The rock is crosscut by thin veins filled with microsparitic and sparite calcite (pictures below, top right). Below the exposed surface, a discontinuous, 0.3÷0.4 mm thick layer shows signs of endolithic hyphal colonization (pictures below, lower left).