ABSTRACT. – Types of Alteration Crusts from Bihor Mountains. Throughout the Bihorului Massif, the petrographic variety has lead to different ways of weathering processes manifestation and has imposed various types of weathered deposits. The products of weathered deposits have various names in scientific literature according to the school that has imposed it. In this paper we used the terms specific to Romanian and French school. Alteration crusts classification had been realized on the basis of field observations and physical and chemical analysis carried out on 12 petrographical categories from where 53 samples of fresh rock and weathered material were collected. Eventually several alteration crusts categories were identified, differentiated by the types of rock on which they were formed.