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A white triclinic mineral that forms rounded, reniform (kidney-shaped) masses of very fine needle-shaped crystals. Ulexite has the unusual optical property of projecting an image of an object placed against a transverse section of it to the opposite surface. It is usually associated with borax deposits and is found in arid environments. Chemical formula: NaCaB5O9·8H2O.
borateborate mineral, NaCaB5O6(OmicronH)65H2O, that consists of hydrated sodium and calcium borate. Individual crystals are colourless and have a vitreous lustre, whereas the more common nodular, rounded, or lenslike crystal aggregates (often resembling cotton balls) are white and have a silky or satiny lustre. It is sometimes called "television rock" or "TV rock" for its fibre-optical properties.