It occurs naturally as tincal (Suhaga) which contains about 50% borax in certain land, lakes. It is also obtained from the mineral colemanite by boiling it with a solution of Na₂CO₃ .

Properties :

(a) Its aqueous solution is alkaline due to hydrolysis,

Na₂ B₄O₇ + 7H₂O ——→ 2NaOH+4 H₃BO₃ .

(b) On heating borax loses its water of crystallization and swells up to form a fluffy mass. On further heating, it melts to give a clear liquid which solidifies to a transparent glassy bead consisting of sodium metaborate ( NaBO₂ ) and boric anhydride ( B₂O₃ ),