In the area of Zwiesel a great diversity of mineralogical compositions can be found and especially the glass manufacturing companies benefited from the outstanding amount of quartz. The most famous mining site is probably the quartz quarry at the mountain Hennenkobel (the name translates as chicken coop) where many rare and popular minerals were found. The mineral Zwieselite, which can be found there, was named after the glass town of Zwiesel.