Umm. Pottery is made of various mixtures of clay and ground minerals... Glass is, like... glass... The difference between a coffee cup and a juice glass... Glass has a non-crystaline structure where ceramics does (have a crystaline structure). Silicon dioxide is the main component of glass. Glass is a mixture of two or more metallic silicates. Clay is the main component of ceramics.
These days it's pretty easy to look up words... glass.... pottery.... ceramics.....
The patterns, colors and glazes as well as the marks (on the bottom of a whole item) can determine the age of a piece. Some patterns are still used today, but there are people who know the slight color differences, pattern differences of old versus new. If you've ever watched Antiques Roadshow, you'd see there are experts who can spot a good old piece- as well as a new piece- from fifty paces. I am not one of those people. But if you go on line and begin to study ceramics, pottery diagnostics in archaeological digs in the U.S., you may learn a thing or two. As with many things, if you're really interested in learning rather than just getting an answer, you're going to have to do a little leg-work. It's possible someone here can tell you what you have- which is cool. But if you spend some time on line looking at examples of old ceramics and pottery, Colonial stuff, things that were typically brought over from England or France or Germany... you'll know more next time you find something. You'll be more self-sufficient.
You can even take some time to look at what Cross Potent or Bill D. (VA)- (to name just two people- here on T-Net) have found during their metal-detecting adventures. They find a lot of things- some of which aren't metal- and which also add evidence as to the age of the site they're digging. There are a lot of resources right here at T-Net- to study. I've spent a lot of time just going through certain members' recent started threads- just to see what they're turning up, day after day. It's very interesting stuff.
So take a look around when you have a chance (better to see on a computer rather than a hand-held device). I think you'll be happy you did!
Thank you everyone for your detailed responses. I feel much more educated and informed in what to look for so for that I thank you.
Since we are on the topic, this piece intrigues me. It appears to be a piece of glazed pottery Which was found an old homestead probably dating to the 1850s or so.
The brown design on the piece is raised which to me implies it was added after the original glazing was added. I have looked around, but I am having a difficult time identifying what this could actually be or based on the cracked porcelain glass, how old it could actually be. It is approximately quarter of an inch thick.
Thanks again everyone, looking forward to your help on my last and final piece.