Kofelsite (4.1 cm across) - kofelsites (also spelled “koefelsites” and “köfelsites”) have the appearance, texture, and feel of pumice. Samples are often called “pumice of Köfels”. They date to about 7815 B.C. (± 100 years) (near-earliest Holocene). The specific origin of kofelsite rocks is uncertain & debated. The rocks are found in a landslide deposit in western Austria. Researchers have suggested that the landslide was impact-triggered. The kofelsite samples in the landslide deposit thus may be impactites (fused rocks from the heat of impact). Some workers have suggested that the rocks are frictionites (fused rocks from landslide heating).