Collmberg consists chiefly of quartzitic Greywacke originating from the Ordovician more than 500 million years ago, also of quartzite and conglomerates. The hill was shaped in the Pleistocene epoch. Collmberg is the site of the oldest known exposed rocks in Northern Saxony. Its Greywacke can be traced towards East-northeast across the neighbouring hills until Weinberg hill near Borna and Käferberg hill near Zaußwitz.