A search in its fourth day now includes the police helicopter, officers on all-terrain vehicles and more than 100 State Emergency Service volunteers.
Police and SES volunteers searched without luck in the Spring Mountain, Springfield Central, Springfield Lakes, Augustine Heights and Brookwater areas at the weekend.
Investigators released more information this morning, revealing Mandala had only recently arrived in Queensland from South Africa.
Officers and her family are concerned because she has a medical condition, speaks limited English and may be disorientated and dehydrated.
They've asked residents, particularly in the Spring Mountain area, to check their yards, garages and sheds for Mandala and review CCTV footage from Friday morning.
Police said Mandala had a dark complexion, slim build and was last seen wearing a black sun hat, white T-shirt and multicoloured wrap skirt.
Her black slides have been found in Spring Mountain, leading police to believe she'll only be wearing blue or purple socks.
Police said she wandered away from a family home in Augustine Heights about 6.40am on Friday and was spotted in nearby Kenneth Drive about 10 minutes later.
She was last seen walking near Broadford Street and Aberdeen Circuit in Spring Mountain between 9am and 10am the same day.
She's thought to be walking or possibly catching public transport to move around.
Police said 102 SES volunteers were searching the area today, as well as Queensland Fire and Emergency Services officers flying drones.
Residents have been asked to keep their drones out of the air.