Mesosiderites are a source of Materials. They can be found on landfall worlds and detected with an SRV's Wave Scanner.
They drop Grade 1, 2, or 4 Raw Materials. These are represented on the wave scanner as 1 bar, close to the bottom.
When they are destroyed by weapons fire from a ship or SRV they explode into chunks of materials, which can be collected using a ship or SRV's Cargo Scoop. Each chunk of a material yields three units of that specific material.