The listing, Amethyst Matrix has ended.
I know this isn't technically an antique, but neither is half the stuff listed under this category. I guarantee that this is likely more than a hundred years old though as crystals like these don't grow over night. I've listed a few other mineral specimens under the collectibles category but figured they'll likely be lost among sports cards and coins. Check them out of this intrigues you. High starting bid since I ship for free and credits just aren't worth what they were a couple of months ago.