Luxembourg is drained by the Sûre (Sauer) and Alzette rivers, both tributaries of the Moselle (Mosel), which forms part of its eastern border. The Ardennes Mts. extend into N Luxembourg. The southwestern section is part of the Luxembourg-Lorraine iron-mining basin, once one of the most productive iron and steel manufacturing regions in the world; Esch-sur-Alzette is its main center. The people are an amalgam of Celtic, French, and German ancestry. In the Letzeburgesch language, which is a prevailing Low German dialect, the duchy is called Letzeburg. German and French are both administrative languages, and English is also widely spoken. The majority of the population is Roman Catholic; there are Protestant, Jewish, and Muslim minorities.