Help with rocks for a Hawaii report...?

I need to list some common rocks of Hawaii and want some help to determine if my answers are okay. Ive got sandstone and limestone from the erosion of coral reefs, basalt from the volcanoes. Obsidian,Gabbro and Olivine. I know Olivine is one because of a green beach, and Obsidian because it is used to make Pele tears- a decoration made from obsidian. Any help would be appreciated.