Museum of Mineralogy / Macle Collection

Macles are "twin crystals" – symmetric concretions belonging to the same mineral species. There are shown typical bonding macles (juxtaposition): rutile, cassiterite, gypsum, calcite, etc.; coalescence macles (penetration): arsenopyrite, staurolite, pyrite, fluorite, quartz, etc., simple as well as multiple ones: aragonite, chrysoberyl, bournonite.