By: nova-an-slc
Image: Robin Rohrback, Mid-Atlantic Geo-Image Collection
License: Creative Commons Non Commercial ⧉

Uploaded: 8 Jan 2021
Last Updated: 25 Jan 2021

493 megapixels
24,704 x 19,964 pixels
82.3 in X 66.5 in at 300dpi
4,276 pixels per inch

This is a volcanic slag formed in the same manner as pumice, but having fewer and larger cavities. It is harder, heavier, and darker than pumice.