Victorian Marble Top Table

Hello! I picked up this table about 4 years ago at a local estate auction.  I purchased it from a decendent of the original owner.  Out of all the auctions and estate sales (even internet searches of furniture) I have been to, I have never seen this type of marble...  It is a very unusual color as one may notice from the pictures.  Does anyone know the name of this type of marble (maybe it is even slate???) and a possible manufacturer?  I liked because I have never seen as table quite like this before!  Thank you very much for all your help!!!

Take a look closely at the marble and see if there are any spots where the color is worn away.  It is hard to tell from photos, but at quick glance it almost looks like faux marble paint - which might help explain why you haven't seen it anywhere before.  The patterns/colors may be an invention of a good faux marble artist.

One of my fireplace mantels is faux marble which you can see in the attached images.

Thank you very much for your information.  The underside of the "marble" is very rough, but has some swirls in the grain.  It almost has the consistency of a rough (concrete-like) slate.  There is writing carved in it in two different places.  One area says "A B    5 1/2"  And another area says "-SEL $13.50"  It even has the name of the original owner written on a piece of paper on the bottom. (I purchased it from the estate of the granddaughter of the original owner).  Anyways, I just always thought the marble was quite unusual with yellows, reds, and purples throughout.  The faux marble paint does make sense.  I guess I have just seen that technique on mantles before, and never on a table.  Thank you again for all your help!!