North of Grad in a small abandoned quarry is a deposit of basalt and pyroclastites which contain olivine nodules. These are oval and sometimes angular in shape, which range in size from one to several centimeters.
Some are covered with a black basalt coating a few centimeters thick. The main mineral in the nodules is olivine, with admixtures of orthopyroxene, brownish-green clinopyroxene and spinel.
Layers of basalt tufa and silty tufa exist here only as small erosion deposits in Goričko. They are nicely exposed in the abandoned quarry north of Grad. Their thickness is only a few hundred meters. This material was transported far from its origins by a strong volcanic eruption. Some of the material was transported by water. The main center of volcanic activity was in neighboring Austria, near Kloch. Basalt tufa and silty tufa are included in the Early Pliocene partially adhered layers of flinty river gravel, sand, loam and clay.