Gemstones do not form in soils.
It is most likely formed underground.
Igneous
lava
you would normally find igneous rock which is formed by cooled magma.
It is most likely to be sedimentary. However both Igneous and metamorphic rocks can manifest a layered structure so this feature is not diagnostic on its own.
It is most likely extrusive.
igneous rocks usally form by cooled magma.
When lava reaches the surface of the Earth through volcanoes or through great fissures the rocks that are formed from the lava cooling and hardening are called extrusive igneous rocks. Some of the more common types of extrusive igneous rocks are lava rocks, cinders, pumice, obsidian , and volcanic ash and dust
most likely as a liquid
Igneous rock
Igneous.
Igneous because islands are USUALLY formed by a volcano erupting and lava cooling....... Hope That helps!