Encyclopedia > Ulexite    Article Content   Ulexite
NaCaB5O9·8H2O (Hydrated Sodium Calcium Borate Hydroxide) is a
mineral occurring in silky white rounded crystalline masses. It
is a hydrous borate of lime and soda. It was named after the
19th century German chemist G. L. Ulex who first discovered it.
Ulexite is a structurally complex mineral, with a basic
structure containing chains of sodium, water and hydroxide
octahedrons. The chains are linked together by calcium, water,
hydroxide and oxygen polyhedra and massive boron units. The
boron units have a formula of B5O6(OH)6 and a charge of -3, and
are composed of three borate tetrahedrons and two borate
triangular groups. Hardness is 2 (softer than a fingernail) and
specific gravity is approximately 1.97.  Ulexite is found with
the mineral borax and is directly deposited in arid regions from
the evaporation of water in intermittent lakes called playas[?].
The precipitated ulexite commonly forms a "cotton ball" tuft of
acicular crystals. Ulexite is also found