I had it as a kid and lost it in 1978. I don’t remember the title but I think it was like the biggest book of magic...
One story was about a guy who invented or found a tube and when he held it up, looked through and blinked, it left a hole in whatever was in view.
Another story (though it might be from a different book) was about a guy who finds clay pebbles in a cave and passed the time tossing them off a cliff. He sticks a couple in his bag and when he gets home from his vacation he discovers that the clay was covering perfect precious gems.