Like Surveyor 3, Surveyor 4 was equipped with a surface claw (with a magnet in the claw) to detect and measure ferrous elements in the lunar surface.
The mission appeared successful until all communications were abruptly lost 2 seconds prior to retro-rocket cutoff at 02:03 UT on July 17, 1967 just two-and-a-half minutes before landing on the Moon. The landing target was Sinus Medii (Central Bay) at 0.4 degrees north latitude and 1.33 degrees west longitude.
NASA believed that the solid propellant retro-rocket might have exploded, destroying the vehicle.
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.