Spilite

Spilite is a type of rock that is made up of dark-colored minerals like basalt or gabbro, combined with light-colored minerals like feldspar.

When volcanoes erupt, they release hot and liquid magma, which is made up of these minerals. Sometimes, the magma flows out of the volcano and cools very quickly on the surface, forming a type of rock called basalt. Other times, the magma cools more slowly underground and forms a type of rock called gabbro.

Now, spilite happens when these rocks are altered by water. Water can seep into these rocks and cause chemical reactions that change their composition. One of the minerals in basalt and gabbro is called olivine. When water reacts with olivine, it converts into a different mineral called serpentine. This process is called serpentinization.

The resulting rock that forms is called spilite. It has a unique appearance because it is made up of dark-colored minerals like basalt or gabbro and light-colored minerals like feldspar, but with a greenish tint due to the serpentine.

Overall, spilite is a type of rock that forms when basalt or gabbro are altered by water and transformed by serpentinization, resulting in a distinctive appearance.