DANALITE

    Class : Silicates
    Subclass : Tectosilicates
    Crystal system : Cubic
    Chemistry : Fe4Be3(SiO4)3S
    Rarity : Uncommon

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

The best danalite crystals come from Yxsjöberg Mine (Sweden) and can measure up to 20 cm. Danalite is also common in several polymetallic veins in English Cornwall (Falmouth, Redruth, Saint-Just, etc...) and well represented in American pegmatites (Pikes Peak, Colorado, Rockport, Massachusetts...). It is also present in different locations in Australia and Canada, as well as in the Mihara fluorite mine (Honshû, Japan).

Photo on the right : Danalite on fluorite from Mt Cleveland Mine, Luina, Heazlewood district, Waratah-Wynyard municipality, Tasmania, Australia © Ralph S Bottrill

Danalite in France

Danalite is not present in the French underground.

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