Ludwigite
Hol Kol Mine, Suan County, North Hwanghae Province, North Korea
Rich sample of black fibrous ludwigite. Size 7,5×5,5 cm. Collection of Geologický pavilon of VŠB-Technical University of Ostrava (http://geologie.vsb.cz/gp ).
© Jakub Jirásek, 2010