“… Close to the Ohra dam south of Luisenthal at the upper end of the Moenchtal lies the agate place of discovery Moenchtal. It is orientated in the older Oberhofer Quarzporphyr. The form of the thundereggs is sometimes irregular, their color varies between light red and whitish. The agate filling of the thundereggs is occasionally not complete, so that in their inside small cavities with quartz crystals may occur…”

written by Johann Zenz , Agates III, Bode publishing house Lauenstein 2011, page 233