This is a Galaxy Stone, or amygdaloidal basalt. This rock forms from lava which cools slowly, leaving bubbles in its wake. The bubbles become vesicles and fill with sedimentary rock. The rocks end up looking like planets, hence the name galaxy stone...
 
But this one is different. It looks like it could be a geode. It has potential. It is too big for our saw or we would have sliced it ourselves. It's about 400 grams and then some. the entire rock seems filled with the same peach to pink coloured material. It might be rhyolite, it might be chalcedony, it could be low grade quartz... But whatever it is, it is pink to peach and seems to be saturated through the whole stone.
 
This will make a fun project for a lapidary artist who wants to saw slices from it. It will shine up nicely if worked a little. This piece came from a rockhounding trip down in South Ayrshire maybe three years ago. It has been sitting around tempting me to smash it ever since. Please, please take it off my hands before I go at it with a hammer.