New data about hydrothermal alterations in the area of Krusha ore occurrence, Western Srednogorie, Bulgaria

The Western Srednogorie is one of the less explored segments of the Upper Cretaceous Apuseni-Banat-Timok-Srednogorie magmatic and metallogenic belt (ABTS). One viable epithermal gold deposit (Milin Kamak) is explored, and several porphyry and epithermal systems are known and were researched in the past. The Krusha ore occurrence is one of the lesser-known ore occurrences in the Western Srednogorie. The presented results of field and petrographic observations, as well as X-ray diffraction add new information about the nature and origin of the hydrothermally altered rocks of the Krusha ore occurrence.