Krakatau is a volcanic island, so the rocks found near it are primarily volcanic rocks. These rocks are formed from the cooling and solidification of magma (molten rock) or lava (magma that has erupted onto the Earth's surface).

Here are some specific types of volcanic rocks you might find near Krakatau:

* Andesite: This is a common rock type found in volcanic areas, including Krakatau. Andesite is a fine-grained, intermediate rock with a composition between basalt and rhyolite.

* Basalt: This is a dark-colored, fine-grained volcanic rock that is very common in oceanic settings.

* Rhyolite: This is a light-colored, fine-grained volcanic rock that is richer in silica than andesite or basalt.

* Tuff: This is a volcanic rock made up of compacted volcanic ash.

Additionally, you might find some sedimentary rocks near Krakatau, which are formed from the accumulation and cementation of sediments. These could include:

* Beach sand: The volcanic activity of Krakatau has created vast amounts of sand, which has accumulated on nearby beaches.

* Coral reefs: Coral reefs can thrive in the warm, clear waters around Krakatau. These reefs contain calcium carbonate from the skeletons of coral animals.

The specific rocks you find near Krakatau will depend on the exact location and the geological history of the area.