Why was "tantrum" trending last week?
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.