Pillow talk

The grey bits are pillow lava formed when a volcano erupts deep under the sea.
The coloured bits are sediments that fall between the pillows and get cooked in the gaps by the heat.
Then a couple of million years later the whole lot gets shoved up in the air, cleaved in half by the upheaval and polished by rain water and scoured rocks rushing down from the summit of the island.
The red bits are jasper, don't know about the green stuff - quartzes with possibly copper or as the gov reckons nickel salts.
We picked a sizeable lump of jasper up in the river bed - a winter project to cut it and polish it perhaps?