Police are conducting a land and air search for a missing prospector, about 30km north of Collie.
John MacKay, 70, set out with a friend near the Bell Brook/Toorak Roads area in Yourdamung Lake around 5pm on Sunday when they became separated.
Police are currently searching the area along with SES volunteers and personnel from the Department of Biodiversity, Conservation and Attractions.
Two helicopters are also searching for Mr MacKay.

The 70-year-old is described as light skinned, approximately 181cm tall, with a solid build, moustache and white hair
He was last seen wearing dark clothing, a wide brimmed hat and steel capped boots.
Concerns are held for his welfare and anyone who sees him, or has information regarding his whereabouts is asked to contact police on 131 444.

PIC: Google Maps
Police issue 31,000 driving infringements in first month of new AI cameras
Works underway on Rockingham and Safety Bay High School redevelopments
New measles exposure sites revealed in Bunbury
Dawesville man charged after allegedly leaving his elderly Great Dane to suffer painful conditions
Good Samaritan sought by police after helping teen during robbery in Baldivis
Under-16s social media ban now in force
Desperate search continues for missing Bunbury FIFO worker
Passengers now able to use credit, debit cards to tag on and off WA's public transport
New floating jetty speeds up emergency response times for Marine Rescue Mandurah