The specific epithet glauca is from the Greek meaning "bluish-grey", referring to the colour of the leaf underside.

[3] Mastixia glauca grows as a tree measuring up to 15 metres (50 ft) tall with a trunk diameter of up to 25 centimetres (10 in).

The pale green fruits are oblong-ovoid and measure up to 4 cm (2 in) long.

[3] Mastixia glauca is endemic to Borneo and confined to Malaysia's Sarawak state where it is known only from Mount Santubong.

[1][2] Its habitat is mixed dipterocarp forests at around 100 metres (300 ft) altitude.