Large Vintage Sterling Silver Fossilized Ammonite Pendant

Vintage sterling silver statement Ammonite slider pendant is marked 925 and features a rectangle black and white stone I think is a Dendrite and an oval faceted black and gray translucent stone that may be a Quartz.  The pendant measures 3 3/4 inches long and the Ammonite has a width of 1 1/4 inches, and the weight of the pendant is 45.2 grams.  There is a chip in the bottom left side of the Ammonite and one on the bottom oval stone at the top near the bezel.