B&W: Man Disables Woman's Car, Supernatural Rock on Coffee Table

by Anonymous
(Florida, USA)

Looking for this old black and white movie about a woman that goes to visit a man in his gothic looking castle / mansion.

The man looks and acts normal, and makes them a cup of tea. He then sneaks out to her car where he disables the engine. Of course the car won't start when she leaves, so he 'kindly' offers for her to stay, which she does.

On the coffee table there's some sort of alien pod / rock with supernatural powers. The guy is trying to make sure she doesn't figure out what it is because it's sitting out in plain view.

Sound familiar? Any suggestions? Thanks!