Danalite - Encyclopedia
Class : Silicates
Subclass : Tectosilicates
Crystal system : Cubic
Chemistry : Fe4Be3(SiO4)3S
Rarity : Very rare
Danalite is a complex silicate of beryllium and iron which forms two continuous series : with genthelvite (zinciferous) and helvine (manganiferous). It is found in granites and its pegmatites, in pneumatolytic and hydrothermal veins, more rarely in zones of contact metamorphism and skarns. It is a mineral that associates with different species depending on the context : cassiterite, albite and muscovite in granites and pneumatolytic veins, magnetite and garnet in skarns, or quartz, fluorite and sulphides in hydrothermal veins. It was named in honor of the American mineralogist James Dwight Dana, professor at Yale University. Danalite can take on various colors : gray, red to flesh pink, red-brown to brown, sometimes yellow. It forms octahedra, dodecahedra and tetrahedra reaching up to 20 cm in edge, and xenomorphic masses.
Main photo : Danalite from Middle Moat Mountain locality, Hale's Location, Carroll County, New Hampshire, USA © Harold Moritz
Danalite in the World
Twinning
No twin known for this mineral species.
Fakes and treatments
No fakes listed for this mineral species.
Hardness : 5.5 to 6
Density : 3.28 to 3.46
Fracture : Irregular to sub-conchoidal
Streak : -
TP : Translucent to transparent
RI : 1.747 to 1.771
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : None
Solubility : Acids
Magnetism : None
Radioactivity : None