Black tourmaline is a "heavy" stone: it's weighty and can help to really get you connected with the Earth. It is also said to be a very protective stone. When I have a hard time winding down from the day and can't sleep, I'll grab one of these and it helps me ground almost instantly, so I can fall asleep.
This listing is for the tourmaline log shown, approximately 4” in length. This is the far right one, in the picture of 3. Weight: approximately 280 grams.