Guys, I found these in Izmir, Turkey. They were on and under the ground. there are hundreds of them. I collected some. I searched a lot but no certain info. Photo with flash they shine a little. They are easy to break. When you break, there is another round stone appears. When I hold tight them, they leave black powder on my hands and can wash with liquid soap, water does not wash away all. They attract magnet but do not attract any other metals. They are heavier than other stones. Does anyone know about these stones?