Hi Tom! I am doing great, thank you! Hope you and yours are the same.
You are correct! The most common size of clay marbles is smaller than the average glass marble. They made clay marbles in all sorts of sizes, from 3/8" or so to over an inch. Most of them were probably around the 9/16" mark. The average glass marble is 5/8". It should be late 1800s to early 1900s.
I’m thrilled with this news Cheese. It came from an old place and was 8” down, I knew it looked right, but the smaller than expected size threw me.