Radiation-Scarred Reviews follows the TRACK OF THE MOON BEAST (1976)

[Saucerman]

http://radiation-scarred-reviews.blogspot.com/2009/07/track-of-moon-beast-1976.html
"An asteroid (portrayed by a charcoal briquette) slams into the Moon, sending chunks of moonrock spiralling into space, most of which burned up in Earth's atmosphere. One made it to Earth though, and grazed Paul's forehead, a fragment of it getting lodged in his brain."