Not so sure how "antique" the board is....but it sure looks like onyx. The stone under looks like perhaps unpolished marble or lime stone...
But the figures are what's interesting. What do they appear to be made from? I suspect they originally went with a different board.
How about closer pictures and a view of the bottom?
Linda c

Hi and thanks for the info. I'm including some more pictures of the pieces themselves. I do seem to remember years ago my mother saying that the pieces were ceramic and hand-painted. Again I'm no expert but in looking at them, they seem to be molded from some kind plaster material. And if they are hand-painted, I would think there would be some kind of artist signature somewhere, but I don't see anything like that. I wouldn't mind getting some info about the pieces too and any info is much appreciated, thanks.
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Interesting set - white onyx and black marble or black-dyed onyx would be my guess for the board.

The figures are probably molded ceramic - bought as bisque and hand painted by a hobbyist. Nicely done.

There may have been a board of yellow and green to go with these - the black and white looks strange with the set.

The pieces appear to be slip molded ceramics. Those would be difficult to play an actual game since there isn't enough difference between the light and dark pieces. Also, the light pieces are not the same color indicating it may be a 'mixed' set. The base of the pieces are sized correctly for the size of the squares. However, chess players would like to see a little more space between the pieces. These pieces would 'play' better on a larger board.

The squares may be of onyx and marble, but could be reconstituted stone. Reconstituted stone is made from small pieces of stone and grindings mixed in a resin and cast. I am puzzled by the backside stones; What holds the board together? I'm thinking there is a composition board such as masonite in the middle with the squares on one side and the backside stones on the other side.

These pieces are known as "decorative", but the pattern does not appear in the current USCF catalog. The style theme may be Crusades.

Most upscale boards are made of hardwoods. It is possible that your board is a one-of-a-kind made by a hobbyist, possibly a lapidarist, and not a mass produced item. It could also be a school shop project.