This exclamation of disappointment is often heard during chert collecting field trips. When looking for Permian cherts in Saxony, one finds the black silicites with white veins of filled cracks abundantly in some places. Rare coloured varieties are easily mistaken for interesting chert samples. The error comes also the other way round: The chunks of silcified peat seen in large amounts in the gravel pit near Nobitz had been mistaken for black silicious rock for a long time and hence regarded as something not worth collecting. However, for those interested in fossiliferous cherts, an occasional close look at a pebble of silicious rock can be rewarding as one may find, with some luck, debris from a marine biotope.

One of the rare interesting samples of silicious rock, incidentally picked up in the gravel pit at Lauta near Senftenberg (Lausitz), is shown in the following. It is a small prismatic fragment with rounded edges. Its geological age has not yet been determined but it is most probably Palaeozoic. The layered deposit contains several distinctly seen spherical objects with sizes below 1mm, some of which are very well preserved. The structure in Fig.2 resembles a sponge. Fig.3 is probably a radiolarian, judging from protrusions pointing radially inward.

						Fig.1: transported silicious rock, total view
						Fig.2: spongy structure in silicious rock
						Fig.3: spherical structure, a radiolarian?