Complex sentence: Inspection of the fulgurite reveals a homogenous glass over a layer of basalt; in between, a stratum made of materials such as feldspar, pyroxene, and olivine exists.
Split into simpler sentences: Inspection of the fulgurite reveals a homogenous glass topping a layer of basalt. In between, a stratum made of materials such as feldspar, pyroxene, and olivine exists.