Stone, Marble, Granite, Tile, Gardening, Gravestones, DIY

Received from an acquaintance.
They said it was marble, but when I searched using Google Lens and other tools, it showed up as granite or similar stone.

The size is approximately 30cm x 30cm, with a thickness of about 6cm. It weighs around 13-14 kg.
There are surfaces that are smooth and others that are rough and coarse. When exposed to light, you can see some sparkling elements.

There are a good number of pieces available, but some have slightly chipped corners. Some pieces have brownish areas, possibly due to rust from metal components or the storage environment/soil. The condition varies from piece to piece.
I've heard from people experienced with stone that even chipped pieces can be processed and repaired for use.

I originally intended to use them as a substitute for tiles or bricks under a wood-burning stove, but I'm not sure of their exact intended use. I've tried laying them in the garden and stacking them to create shelves for pots.

I lack specialized knowledge, so I may not be able to answer your questions. However, if you are someone who can process or utilize these stones for your own purposes, please feel free to contact me.
Please also inquire about the quantity.
Due to the weight, we can discuss shipping methods, costs, and pricing based on the number of pieces. Please use the comment section. It would be greatly appreciated if you could pick them up in person.