This is a wonderful piece. A striking French slate tazza. 
A tazza is a mantle stand, perfect for a chunky church candle or a plant if you prefer. 
It would originally have had a twin, so would have been part of a pair and they would have stood either side of a matching mantle clock. 
Possibly circa 1930’s. Very decorative. 
Measurements: 17.5 x 11.5 x 26cm high