My periodic table poster is now available! Manganese oxides in quartz. Description from the source: Mn oxides included in Quartz. Minas Gerais, Brazil. 6x2,5x2,5 cm; 40 g. Source: Simone Citon Contributor: John Gray Acquired: 26 October, 2008 Text Updated: 26 October, 2008 Price: Trade Size: 2.4" Composition: MnO2+SiO2