This is a flat bottomed agate. This happens when the bubbles which form under slow cooling lava while the holes in the rock are forming don't get off the ground. Instead, the minerals which leak in over the years to create the sedimentary agate rocks hit a flat bottom and spread out.
As is normal with these flat bottomed Scottish agates there are a few layers on the bottom, known as waterline or water level agates. some of these lines wore away in the tumble but you can still see two strong ones Above the lines there is a quartz pocket with perhaps a second pocket or a calcite pocket inside it. The upper layer of white inside the top of the agate is leaking down into the quartz in plumes.
There's a lot going on in this little agate from Scotland.
This is a plume agate/waterline agate from Ayrshire in Scotland. We tumble it in the rock tumbler to get a bit of a shine on it.
