Antique Marble and Brass Lamp Finale

This finale is rather out of my expertise since I’m not very familiar with marble – or lamps either!  The marble appears in good condition other than needing the edges smoothed out and cleaning. The brass portion coming out of the bottom appears slightly cocked (you can see it in the photo). I suspect that the brass is removable from the marble but, again, I’m not an expert on these.  The separate brass piece screws into the bottom for a purpose unknown to me.

For size reference the marble is 1-3/8” high and 1-5/8” diameter