The stone is from Nantucket. It has grey greenish color with som etanand brown.
The wire is solid copper that has been oxidized for an antique look. Antique copper-plated brass cable chain, 18". Please note that copper naturally darkens with age and if necessary may be cleaned to lighten it back up, a polishing pad is included with your order.  The last photo shows back of the pendant, it is next to a ruler for size comparison.