A
specimen of Ulexite that has been cut top and bottom with a diamond saw.
This view shows the silky texture produced by the fine, acicular crystal
growth. Locality - Boron, California
When viewed parallel to the fibers, Ulexite transmits light in a similar
fashion to fiber optics. It is this property that has given rise to it
nickname of "TV" stone.
CHEMISTRY NaCaB5O9 .8H2O Hydrated sodium calcium borate
CRYSTALLOGRAPHY Triclinic
CRYSTAL GROWTH AND HABITS Ulexite is usually found in rounded masses of fine fibrous crystals. Masses of Ulexite are often called "cotton balls".
COLOR AND OTHER OPTICAL PROPERTIES Ulexite is white to lightly colored by impurities, commonly clay. Its unique optical property is that is transmits light along the long axis of the crystal by internal reflections, very much in the same way as in fiber optics. Clay particles often hinder this light transmission.
HARDNESS 2.5 but Ulexite breaks very easily
SPECIFIC GRAVITY 1.96
LUSTER SIlky
STREAK White
BREAKABILITY Very brittle with a prismatic parting
OCCURRENCE Ulexite is an evaporite mineral found in the arid playa lakes of the southwestern United States.
ASSOCIATED MINERALS Borax, colemanite, halite, trona, mirabilite
OTHER PROPERTIES Ulexite often alters to gypsum and colemanite.
NAME in honor of the German chemist G. L. Ulex, the discoverer of the mineral.