Prostanthera rhombea, commonly known as sparkling mintbush, is a shrub that is native to south-eastern Australia It has an open habit, growing to between 0.5 and 2 metres high. The aromatic leaves are 2 to 6 mm long and 2 to 5.5 mm wide. The flowers are mauve or bluish and appear in spring. The species was formally described in 1810 by Robert Brown. It occurs in New South Wales and Victoria.