YUGAWARALITE

    Class : Silicates
    Subclass : Tectosilicates
    Crystal system : Monoclinic
    Chemistry : CaAl2Si6O16 4H2O
    Rarity : Very rare

Yugawaralite is a very rare mineral belonging to the zeolite group. It is a mineral of active and extinct geothermal areas, which occupies the cracks and cavities of rhyolites, dacites or basalts, and is deposited at the level of geysers or hot springs. It owes its name to its locality of discovery : Yugawara (Japan). Yugawaralite occurs in flat tabular crystals that can reach 8 cm; they are sometimes assembled in subparallel aggregates.

Main photo : Yugawaralite from Malad Quarry, Mumbai, Maharashtra, India

Yugawaralite in the World

The island of Honshû in Japan is particularly rich in occurrences of yugawaralite : Shimoda, Toi, Yugawara, etc... The geysers of the Lower Geyser Basin in Yellowstone Park (Wyoming) also deposit small quantities of this mineral. Finally, let us mention an atypical deposit for it : the large basalt quarries of Khandivali near Mumbai (India), which have also provided extraordinary crystals of other minerals from the zeolite group.

Yugawaralite in France

In France, yugawaralite is known in Cilaos on the of Réunion island.

Right photo : Yugawaralite de Cilas, La Réunion island, France © Joy Desor

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 4.5 to 5
Density : 2.20 to 2.23
Fracture : Conchoidal
Streak : White

TP : Translucent to transparent
RI : 1.492 to 1.504
Birefringence : 0.010
Optical character : Biaxial (+/-)
Pleochroism : None
Fluorescence : None

Solubility : Hydrofluoric acid

Magnetism : NoneRadioactivity : None