Dannemorite - Encyclopedia
Class : Silicates
Subclass : Inosilicates
Crystal system : Monoclinic
Chemistry : Mn2(Fe,Mg)5Si8O22(OH)2
Rarity : Rare
Dannemorite (recently renamed clino-ferro-suenoite) belongs to the group of monoclinic amphiboles. It is a rare manganiferous amphibole, which forms a series with tirodite, which is found in metamorphosed manganiferous rocks and formations poor in iron. Its name is taken from its locality of discovery : Dannemora (Sweden). Dannemorite occurs in prismatic to fibrous crystals no larger than 1 cm, dark brownish green or greenish gray in color.
Main photo : Dannemorite from Stollberg orefield, Väster Silvberg, Smedjebacken, Dalarna County, Sweden © Vandall King
Dannemorite in the World
Twinning
Twins are known and parallel to {100}.
Fakes and treatments
No fakes listed for this mineral species.
Hardness : 5 to 6
Density : 3.1 to 3.6
Fracture : Irregular
Streak : White
TP : Opaque to transparent
RI : 1.639 to 1.708
Birefringence : 0.025 to 0.037
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : None
Solubility : Insoluble
Magnetism : None
Radioactivity : None