Agate geode

This is close up of a slice of another agate geode. I have two of these, brought back from a holiday so long ago I'm not sure where we were. They are particularly beautiful with the light shining through them, see extras. 

Not having much idea what these actually were I turned to the internet. for a bit of Blip learning.

Geodes can form in any cavity, but the term is usually reserved for more or less rounded formations in igneous and sedimentary rocks. They can form in gas bubbles in igneous rocks, such as vesicles in basaltic lava; or, as in the American Midwest, in rounded cavities in sedimentary formations. After rock around the cavity hardens, dissolved silicates and/or carbonates are deposited on the inside surface. Over time, this slow feed of mineral constituents from groundwater or hydrothermal solutions allows crystals to form inside the hollow chamber. (Wikipedia)
The blue colour in mine is dye added to make them more attractive to tourists. The first extra is yesterday's effort for abstract Thursday. It has horizontal bands and is a gravitationally banded agate, with the layers laid down like sediment. The other is the more usual type where the layers are built up from the outside inwards.
Anyway I think they are jolly lovely, perhaps I have room for a few more?